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Tutors Answer Your Questions about Geometry proofs (FREE)
Question 238587: he is 21 years old
Found 2 solutions by magnifik0, scott8148:
Answer by magnifik0(1)   (Show Source):
Answer by scott8148(3382)  (Show Source):
You can put this solution on YOUR website!X-10= age of eric 10 years ago
Eric is now 3 times as old as he was 10 years ago: 3(X-10)
X is his age now
3(X-10)=X
3X-30=X
2X=30
X=15
Question 240532: Solve each of the following equations for y in terms of x.
3/4(2x-4y)=9
Answer by Alan3354(6092)  (Show Source):
Question 240126: Given: L is the midpoint of line segment IE, line segment NE is congruent to NI. Prove that line segment NI bisects angle INE
Answer by solver91311(5072)  (Show Source):
Question 239626: I dont understand clearly how to do geometry proofs working with isosceles triangles and the rest of chapter 4 in geometry...can you please help me?
Answer by College Student(210)  (Show Source):
You can put this solution on YOUR website!Hello! I'll try to summarize some things here for you.
.
As we you know, all triangles have 3 sides forming 3 angles.
The sum of all angles must always add up to 180 degrees.
In the case of isosceles triangles, 2 of its sides and 2 of its angles must equal to each other. It does not matter their measurement, as long as both are the same.
There is one kind of isosceles triangle that we call a "right isosceles triangle". This triangle has one angle of 90 degrees and the other 2 are exactly 45 degrees each.
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If you need to see some illustrations, I recommend: http://www.mathsisfun.com/triangle.html
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I hope this helps you. Otherwise, please keep posting questions.
Question 239628: Please help me with this proof.
Given: Triangle RST is congruent To triangle PSA
Prove: PART is a parallelogram.
Thank you.
Answer by solver91311(5072) (Show Source):
You can put this solution on YOUR website!
Can't help you. It is not true that any two congruent triangles that share a vertex create a parallelogram with the unshared vertices. Hence, there is something missing from your description of the problem. Sorry.
John
Question 239582: I need help with a proof?
Answer by College Student(210) (Show Source):
You can put this solution on YOUR website!Please submit your problem with the answer you got (if any). We respond to many kinds of problems. Right now we are not sure what area you need help with.
Question 239199: If two angles are congruent and supplemmenatry, then the measure of each is 90 degrees, IS that right. Please explain? I am very confused.
Answer by College Student(210) (Show Source):
You can put this solution on YOUR website!Congruent angles are angles of the same degree. It doesn't matter how many degrees they are as long as they measure the same when compared.
.
Supplementary angles are angles that add up to 180 degrees. It doesn't matter where they are drawn as long as they add up to 180.
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Now, if you have two angles that are BOTH congruent and supplementary, then they must measure 90 degrees each. This will cover both definitions as they would have the same measurement AND they add up to 180 degrees.
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:)
Question 236699: Do you know the answer of the folloging question, or the steps to solve it?
Given: M is the midpoint ofPQ
MQ = QN
Prove: PM = Qn
Answer by College Student(210) (Show Source):
You can put this solution on YOUR website!If M is the midpoint of PQ, then by definition PM = MQ. Therefore, if PM is equal to another segment (in this case QN), then MQ is also equal to QN.
Question 238704: Question: Write Equations of the line that passes through the given points in point-slope form and slope-intercept form.
Problem: x-intercept is -6 ; y-intercept is 2
Point-slipe form:_______________
Slope-intercept form:__________
Answer by College Student(210) (Show Source):
You can put this solution on YOUR website!The equation for a Point-Slope Form of a line is:
.
The equation for Slope-Intercept Form of the Line is:
.
Now, all we need to do is substitute the x and y values to answer the question.
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Problem: x-intercept is -6 ; y-intercept is 2
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In the Point-Slope eqn, you substitute the x1 and y1 variables. So:
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Slope-intercept form:
Question 238520: Write the inverse, converse and contrapositive of the following conditional, and state whether each is true or false
If your computer screen is turned on, then you will see pictures.
Answer by nyc_function(260)  (Show Source):
You can put this solution on YOUR website!
If your computer screen is turned on = p
then you will see pictures = q
INVERSE: If not p, then not q.
If your computer screen is not turned on, then you will not see pictures.
CONVERSE: If q, then p.
If you see pictures, then your computer screen is turned on.
CONTRAPOSITIVE: If not q, then not p.
If you do not see pictures, then your computer screen is not turned on.
I'll let you decide if each statement is true or not.
Question 238515: Prove the following statement:
If a triangle has one obtuse angle, then the other two angles are acute.
Found 2 solutions by nyc_function, Fombitz:
Answer by nyc_function(260) (Show Source):
You can put this solution on YOUR website!An obtuse angle is an angle whose measure is more than 90 degress but less than 180 degrees.
The sum of the measures of the angles of a triangle is 180 degrees.
Given a triangle having one obtuse angle, it follows that the other two angles must be acute or less than 90 degrees because the sum of the angles of a triangle = 180 degrees.
Answer by Fombitz(2113)  (Show Source):
You can put this solution on YOUR website!For every triangle,
where A,B,C are the angles.
An obtuse angle is an angle greater than 90 degrees.
Let A be an obtuse angle.
Then A=90+e, where e is a positive value, less than 90.
B and C cannot equal 0.
Then
which means they are both acute.
Question 237789: How do i write a proof to show that mesure of angle 1 is equal to the mesure of angle 3 if mesure of angle 2 equals mesure of angle 4.
I'm very bad at proofs.
i dont even know were to begin.
Answer by solver91311(5072) (Show Source):
You can put this solution on YOUR website!
Well, no one here will be able to help you unless you give us the diagram so that we can see the relationship between your various angles.
In general, start from what you are given. I suspect with this one you will probably want to show that 2 equals 1 and 3 equals 4 so 1 has to equal 3 by the transitive property of equality. But not having the diagram, I don't know what to tell you about how to show that 2 equals 1 or that 4 equals 3 (or vice versa, if appropriate).
John
Question 237651: do you solve proofs if i give you the given and what i need to prove?
Answer by College Student(210) (Show Source):
You can put this solution on YOUR website!Go ahead and post what you need. A tutor will respond at some point. Please be patient, it might take more than a day. There are many tutors that log on at different times and each answers those we can provide a correct answer.
Question 237403: Prove triangle ABC is isoceles
Given: angle BAD is congruent to angle CAD
line segment AD is perpendicular to line segment BC
The answers that I originally gave were:
statement: BD is congruent to CD
reason: definition of a bisector
statement: angle BAD is congruent angle CAD
reason: ray AD is the bisector of angle BAC (given)
statement: AD is equal to AD
reason: reflexive property of equality
statement: triangle ABD is congruent to triangle ACD
reason: SAS of congruency of triangles
statement: angle ABD is congruent to angle ACD
reason: CACT
grading comments: While the effort is appreciated, the proof contains several errors. revise.
Found 2 solutions by solver91311, Edwin McCravy:
Answer by solver91311(5072) (Show Source):
You can put this solution on YOUR website!
Your first step is in error. Where did you get the information that anything bisected anything else? Just because in the picture AD looks like a bisector of BC, and the fact that AD will ultimately turn out to be a bisector of BC, unless you are given the fact that it is a bisector or can prove from the information that you were given that it is a bisector, you cannot assume that it is.
"Objection! Assumes facts not in evidence!"
"Sustained."
Your second step: Again with the bisector thing. No, BAD congruent to CAD because it is given that BAD congruent to CAD.
Your third step is properly constructed and justified.
Your fourth step is the crux of your problem. Instead of SAS, you should be using ASA.
Just follow the bouncing ball:
1. BAD congruent to CAD -- Given
2. AD congruent to AD -- Reflexive property of equality
3. BDA is a right angle -- Definition of perpendicular
4. CDA is a right angle -- Definition of perpendicular
5. BDA congruent to CDA -- Transitive property of equality
6. Triangle BDA congruent to Triangle CDA -- ASA
7. AB congruent to AC -- Corresponding sides of congruent triangles
8. Triangle ABC is isosceles -- Definition of isosceles
QED
John
Answer by Edwin McCravy(2922) (Show Source):
You can put this solution on YOUR website!
statement: ∠BAD ≅ ∠CAD
reason: given
statement: AD ≅ AD
reason: a line segment is congruent to itself
statement: m∠ADB = 90°
reason: given AD is perpendicular to BC
statement: m∠ADC = 90°
reason: given AD is perpendicular to BC
statement: ∠ADB ≅ ∠ADC
reason: both angles have measure 90°, i.e., they are right angles.
statement: ∆ABD ≅ ∆ACD
reason: ASA of congruency of triangles
statement: AB ≅ AC
reason: CSCT. or corresponding sides of congruent triangles.
statement: ∆ABC is isosceles
reason: ∆ABC has two sides congruent.
Edwin
Question 237402: Okay, so im doing Properties, Definitions, Theorems & Proofs in class and i need a bit of help.
How do you write a proof for this given:
∠FOG ≅ ∠IOH
(if the symbols dont show up, the first one is an angle sign, the second is a congruent sign, & the third is another angle sign).
Answer by solver91311(5072) (Show Source):
You can put this solution on YOUR website!
That would depend a great deal on what it is you are trying to prove. You need to provide a properly labeled figure and a statement of what it is that you want to prove.
If all you need is a statement of the reason that ∠FOG ≅ ∠IOH and it truly is a given, then the proof reason is simply "Given"
John
Question 237139: A bottled water company charges $8 per month for a water cooler and $5 per bottle b of water. Write an equation that represents the total cost C for monthly water service.
Answer by rfer(2688) (Show Source):
Question 237001: How many answers can there be for a proof? Say you put "definition of congruent angles" but the real answer is "vertical angle theorem", aren't they the same thing basically? yes, vertical angle theorem says that they share a vertex, but they are also congruent so shouldn't they both be accepted?
Answer by solver91311(5072) (Show Source):
You can put this solution on YOUR website!
Apples and bananas are both fruit, but they aren't the same thing. Would you say that the Reflexive Property of Equality is the same as, say, the Commutative Property for Multiplication? Why not? They both have an equals sign in them. The Definition of Congruent Angles tells you exactly what congruent angles are. The Vertical Angle Theorem proves that a particular pair of angles is congruent. Two completely different ideas. I can't see the proof to which you allude, but I highly suspect that you would not be able to satisfy the definition of congruence at the particular step in question, whereas you can demonstrate that the angles are vertical angles and are therefore congruent.
John
Question 236863: The statement x(y+z) = xy + yz is an example of what type of property or equality?
Thanks for your help.
Found 2 solutions by Earlsdon, jim_thompson5910:
Answer by Earlsdon(4900) (Show Source):
You can put this solution on YOUR website! ??? I don't know what is demonstrated by this!
Perhaps you meant to write:
 ?
If so, then this demonstrates the distibutive property.
Answer by jim_thompson5910(13794) (Show Source):
Question 236672: Proof Assignment:
I Made the picture in Ms Paint, and posted it on photo bucket, this is my first time doing this, i hope one of my picture links works. Thanks again!
[URL=http://s971.photobucket.com/albums/ae197/marksc92/?action=view¤t=Proof1.jpg][IMG]http://i971.photobucket.com/albums/ae197/marksc92/th_Proof1.jpg[/IMG][/URL]
Answer by jim_thompson5910(13794) (Show Source):
You can put this solution on YOUR website!With this proof, the trick here is to show that triangle EHG is congruent to triangle EFG. From there, you can use CPCTC (Corresponding Parts of Congruent Triangles are Congruent) to show that angle EHG is congruent to angle EFG
Question 236678: Please help me with this proof:
Answer by jim_thompson5910(13794) (Show Source):
You can put this solution on YOUR website!The goal here is to show that angle 1 = angle 4. If we can do that, we've then equivalently shown that line segment BF bisects angle ABC.
Question 236449: can you please help me? I don't know what to do
# of sides=?
measure of each exterior angle=?
measure of each interior angle-165
i know to find the interior angle you do 180(n-2)
Answer by jim_thompson5910(13794) (Show Source):
You can put this solution on YOUR website!For any n-gon (ie a polygon with 'n' sides), the sum of the interior angles can be found by  . Divide this sum by the number of sides 'n' to get  which is the measure of a single interior angle.
Since the measure of each interior angle is 165 degrees, this means that 
Start with the given equation.
 Multiply both sides by 'n'.
 Distribute.
 Add  to both sides.
 Subtract  from both sides.
 Combine like terms on the left side.
 Divide both sides by  to isolate  .
 Reduce.
So the polygon has 24 sides.
Question 235903: EG=13, ef=3
Answer by nyc_function(260) (Show Source):
Question 235779: I need help on solving a proof
Answer by nyc_function(260) (Show Source):
Question 235610: what is the quickest way to memorize all of the proofs in geometry?
Answer by solver91311(5072) (Show Source):
Question 235123: given: m<1 + m<2 = 180
Prove: a//b
Answer by Alan3354(6092) (Show Source):
Question 234739: please help me solve this proof
The formula learned for slope is m= y2-y1/x2-x1. use an algebraic proof to show that the slope can be claculated using the equation m= y1-y2/x1-x2
Answer by Alan3354(6092) (Show Source):
You can put this solution on YOUR website!The formula learned for slope is m= y2-y1/x2-x1. use an algebraic proof to show that the slope can be claculated using the equation m= y1-y2/x1-x2
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y1-y2 = -(y2-y1)
Same with the x terms
It's both NUM and DEN times -1, which is no change.
Question 234687: What are all of the geometric proofs
Answer by solver91311(5072) (Show Source):
Question 234696: Can yu please help me solve this proof?
Given:
prove: line MO is parralle to line RP
Answer by solver91311(5072) (Show Source):
Question 234599: Find the value of x so that angleABC is a right angle, given the following coordinates : A(x,7) B(-3,x) C(-1,0)
Answer by Alan3354(6092) (Show Source):
You can put this solution on YOUR website!Find the value of x so that angleABC is a right angle, given the following coordinates : A(x,7) B(-3,x) C(-1,0)
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AB is perpendicular to BC.
slope of AB = (7-x)/(x+3)
slope of BC = x/(-3+1) = -x/2
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the slopes are negative inverses
(x+3)/(7-x) = x/2
2(x+3) = x(7-x)
-x^2 + 7x = 2x + 6
x^2 - 5x + 6 = 0
x = 2
x = 3
Question 160235: ._____._________._____.
A B C D
Statements Reasons
AC=BD GIVEN
AC=AB+BC Def. of Betweenness
BD= BC+CD Def. of Betweenness
AB+BC=BC+CD SUBSTITUTION PROPERTY
BC=BC REFLEXIVE PROPERTY
AB=CD TRANSITIVE PROPERTY
Answer by smartguy101(5) (Show Source):
You can put this solution on YOUR website!deanice, u r really really really really really really really really really really really really really really really really HOT!!!!!!!!!!!!!!!!!!!!!!!!!!!1
Question 234187: Hi I'm currently doing home school and I have geometry. My question is how do you know if it's SSS, ASA or SAS in a proof? I've been doing good answering the problems, but I've only been guessing. I want to understand it better, I'm going to do state testing next couple of months.
Thanks.
Answer by solver91311(5072) (Show Source):
You can put this solution on YOUR website!
There are three ways to prove that two triangles are congruent. Either all three sides have equal measure (Side-Side-Side or SSS), two angles and the side between them all have equal measures (Angle-Side-Angle or ASA), or two sides and the angle between them have equal measures, (Side-Angle-Side or SAS). Depending on your proof, you choose the one that you are able to demonstrate. For some proofs, it is possible that it can be done more than one of the ways, and for others, there may only be one way -- and that is the problem: figuring out which of the three ways is going to work and then how you get there starting at the givens. Sometimes intuition works well, sometimes creativity helps, and sometimes you just have to use good old trial and error. Sorry, no magic formulas or bullets here.
John
Question 234105: If a quadrilateral has at least one right angle, then it is a rectangle
Answer by Alan3354(6092) (Show Source):
You can put this solution on YOUR website!If a quadrilateral has at least one right angle, then it is a rectangle
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False. The angles can be, for example, 90, 80, 80, 110 degrees.
1 counter example is sufficient to disprove.
Question 231633: How do you solve ab/2 + ab/2 + cxc/2
Answer by Alan3354(6092) (Show Source):
Question 233561: I am in the 10th grade. I havee Geometry. I would like to know when do you use definations: 1. Medium, 2. bisector, 3. perpendicular 4. altitude 5. perpendicular bisector
Answer by Alan3354(6092) (Show Source):
Question 233502: can a median be an altitude?
Answer by Alan3354(6092) (Show Source):
Question 233169: how do i prove
if the diagnols of a parallelogram are congruent the parallelgram is a rectangle
Answer by Theo(675)  (Show Source):
You can put this solution on YOUR website!If it is a parallelogram, then the opposite sides are equal.
If the diagonals are also equal, then you have 4 congruent triangles.
Let your parallelogram be ABCD where:
A is top left corner.
B is top right corner.
C is bottom right corner.
D is bottom left corner.
Opposite sides are:
AB and CD
AD and BC
Diagonals are:
AC
BD
Triangles that are congruent are:
ADC with CBA by SSS because:
AD = BC
AC = AC
AB = DC
This means that angle ADC = angle ABC because congruent angles of congruent triangles are congruent.
BCD with DAB by SSS because:
AD = BC
DC = AB
BD = BD
This means that angle DAB equals angle BCD because congruent angles of congruent triangles are congruent.
Since the opposite angles of a parallelogram are supplementary (sum of their angles is equal to 180 degrees), this means that:
angle ADC = 90 degrees
angle ABC = 90 degrees
angle DAB = 90 degrees
angle BCD = 90 degrees
This means that parallelogram ABCD is a rectangle because a rectangle is a parallelogram with all angles being 90 degrees.
Question 232517: I'm trying to do the proofs myself because I know they are important, but I'm just having trouble moving from one step to another. It's hard for me to figure out what comes next after each statement. Do you have any tips for me?
Answer by ly12603(33)  (Show Source):
You can put this solution on YOUR website!i myself am learning about proofs right now, but something that did come up and i use often is the REFLEXIVE postulate. thats when two triangles share a same side its equal to its self, usually that is the end of the SSS(side side side) ASA (angle side angle) or SAS (side angle side) that you have to use. one websight that i like to go on is http://www.sparknotes.com/math/geometry3/geometricproofs/problems.html for begining problems, any more help needed feel free to e-mail me @ ly12603@yahoo.com ill try and help as best i can :]
Question 232123: how do i solve for a proof?
Answer by solver91311(5072) (Show Source):
You can put this solution on YOUR website!
Start with what you are given, then proceed in logical steps showing the axiomatic or provable reason for each step, until you arrive at whatever it is you are trying to prove.
John
Question 231650: given: 3(x-2)=15
prove: 7=x
Answer by rfer(2688) (Show Source):
Question 229434: Given 10(x+3)=4x+6
prove x=-4
Answer by drj(1380)  (Show Source):
You can put this solution on YOUR website!Given 
prove x=-4
Step 1. Multiply out the left side of the equation to get rid of the parenthesis.
Step 2. Subtract 30 from both sides of the equation
Step 3. Subtract 4x from both sides of the equation
Step 4. Divide 6 from both sides of the equation
Step 5. Check as a solution by substituting into original equation
 which is a true statement.
Step 6. ANSWER: The solution is . Steps 1-5 shows the proof.
I hope the above steps were helpful.
For FREE Step-By-Step videos in Introduction to Algebra, please visit http://www.FreedomUniversity.TV/courses/IntroAlgebra and for Trigonometry visit http://www.FreedomUniversity.TV/courses/Trigonometry.
And good luck in your studies!
Respectfully,
Dr J
http://www.FreedomUniversity.TV
Question 228974: 3(2x – 4) = 2x – 1
Answer by rfer(2688) (Show Source):
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