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Tutors Answer Your Questions about Geometry proofs (FREE)
Question 235903: EG=13, ef=3
Answer by nyc_function(155)   (Show Source):
Question 235779: I need help on solving a proof
Answer by nyc_function(155) (Show Source):
Question 235610: what is the quickest way to memorize all of the proofs in geometry?
Answer by solver91311(4818)  (Show Source):
Question 235123: given: m<1 + m<2 = 180
Prove: a//b
Answer by Alan3354(5863)  (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(5863) (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(4818) (Show Source):
Question 234696: Can yu please help me solve this proof?
Given:
prove: line MO is parralle to line RP
Answer by solver91311(4818) (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(5863) (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(4818) (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(5863) (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(5863) (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(5863) (Show Source):
Question 233502: can a median be an altitude?
Answer by Alan3354(5863) (Show Source):
Question 233169: how do i prove
if the diagnols of a parallelogram are congruent the parallelgram is a rectangle
Answer by Theo(549)  (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(4818) (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(2588) (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(2588) (Show Source):
Question 228921: given: is 8x-5=2x+1
prove: x=1
I dont understand how to find the reasons in a 2 column proof
Answer by chibisan(120)  (Show Source):
Question 226776: wat is the point of proving a theorum if its already created and we know its true
Answer by rfer(2588) (Show Source):
Question 226070: HELP
given: angle 1 and angle 2 are supplementary
angle 3 and angle 2 are supplementary
Prove: angle 1 and angle 3 are congruent
Answer by solver91311(4818) (Show Source):
Question 224020: given <1 = <2
prove
Answer by rapaljer(3526) (Show Source):
Question 224021: given <1=<2 prove
Answer by rapaljer(3526) (Show Source):
Question 223861: I really dont get how to do proofs and such. We just started on them in Geometry but our teacher completely lost me. The homework seems like it is written in a foreign language to me.
The problem is:
Suppose point T is the midpoint of RS and point W is the midpoint of RT. If XY = (supposed to be about equal to) RT and TS has a length of z, write the length of the segment in terms of z for RT.
Answer by MLipsky(9) (Show Source):
You can put this solution on YOUR website!
At least you're trying. That's the most important thing.
With a problem like this, your only hope of getting it is to draw pictures. PLEASE IGNORE ALL NUMBERS.
"Suppose point T is the midpoint of RS"
" . . . and point W is the midpoint of RT"
"If XY is equivalent to RT "
"and TS has a length of z"
"write the length of the segment in terms of z for RT."
The numbers make it harder to see, but I hope you can tell that XY is equivalent to TS. So, in terms of z, XY equals  . It seems complicated, because of the way it's written, but it's not complicated. If they want some written proof, I suppose you could say that since T is the midpoint, then RT is equivalent to TS. And XY is equivalent to RT (given). Therefore, XY must be equivalent to TS.
For tutoring, please visit 
Question 223494: Given that WX=YZ
Prove that WY=XZ
Answer by Alan3354(5863) (Show Source):
Question 223298: My daughter has the question that states, construct a square wit perpendicular z
I have no idea how to help her.
Answer by Alan3354(5863) (Show Source):
You can put this solution on YOUR website!My daughter has the question that states, construct a square wit perpendicular z
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That's all it says?
Construct it out of what? Plywood?
Perpendicular to what?
Question 222443: Prove that if -1/2x=9,then x=-18.
Answer by user_dude2008(690) (Show Source):
Question 222117: given AB congruent to AC,BDE, CDF, AFE, BE bisects CF and AE is parrallel to BC
prove BD is congruent to CF
THANKS
Answer by solver91311(4818) (Show Source):
Question 222136: if m<1=145, find m<2, m<3, and m<4.
Answer by solver91311(4818) (Show Source):
You can put this solution on YOUR website!
You aren't likely to get much help without at least describing the figure. The way you stated this, the measures of angles 2, 3, and 4 could be anything. Sorry, but none of us are clairvoyant.
John
Question 221424: I am having a really hard time with proofs in geometry. This problem comes from the Essentials of Geometry for College Students; Chapter 2.5, exercise 19:
Given: Line Segment (LS) AB is congruent to LS DE; LS AB is perpendicular to LS BD; and, LS DE is perpendicular to LS BD.
Prove: LS AC is congruent to LS EC
I can see that the figure is clearly 2 right angles adjacent to one another making them equal in measure; that point C is the midpoint of LS AE and LS DE as well as the vertex of both Triangles ABC and EDC. But, the trouble I'm having is putting them into a logical sequence. I know I have to prove one thing to move onto the next but putting them in the right order is difficult because there are so many ways to get the same answer. Can you help me with any tips that will make this process easier for me?
The answer to this specific question is given in the back of the book but I'm more interested in the process than the answer. I need to train my brain to think linearly which is what these types of exercises will do. The teacher I have isn't really helping much or should I say, isn't speaking in terms that are clicking with me.
I look forward to your response.
Thank you,
Cheri
Answer by jim_thompson5910(13679) (Show Source):
You can put this solution on YOUR website!I'm having a hard time visualizing the problem. Can you post an image of it? If you need help posting images, check out this lesson.
The basic goal is to show that triangle ABC is congruent to triangle CED. From there, you can show that AC is congruent to EC because their corresponding parts are congruent.
Here's another way to prove this in a two column proof:
Notes:
1) CPCTC stands for Corresponding Parts of Congruent Triangles are Congruent.
2) I used the theorems and postulates from this page and this page
3) In statement 5, recall that vertical angles are congruent to one another.
4) AAS stands for Angle Angle Side. I used the angles ACB and DCE for the first 'A', the angles ABC and CDE for the second 'A', the sides AB and DE for the 'S'
Question 221313: prove that if 4x-4=3y+6 and y=2x then x=-5
by substitution y=2x so 4x-4 = 3(2x)+6
4x-4=6x+6
-4x from both sides -4=2x+6
-6 from both sides -10=2x
divide both sides by 2 -5=x
Found 2 solutions by purplerain, drj:
Answer by purplerain(1) (Show Source):
You can put this solution on YOUR website!prove that if 4x-4=3y+6 and y=2x then x=-5
by substitution y=2x so, 4x-4 = 3(2x)+6
simplified expression becomes, 4x-4=6x+6
-4x from both sides, 4x-4x-4=6x-4x+6 equals -4=2x+6
-6 from both sides , -10=2x
divide both sides by 2, therefore -5=x or x=-5
Answer by drj(1380) (Show Source):
You can put this solution on YOUR website!prove that if 4x-4=3y+6 and y=2x then x=-5
Step 1. Substitute the values of x and y into the equation to see if it leads to a true statement.
Step 2. Find y when x=-5. Then y=2*(-5)=-10.
Step 3. Substitute x=-5 and y=-10 into 4x-4=3y+6
4*(-5)-4=3(-10)+6
-20-4=-30+6
-24=-24 which is a true statement.
Step 4. ANSWER: x=-5 and y=-10 satisfies both y=-2x and 4x-4=3y+6.
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.
Good luck in your studies!
Respectfully,
Dr J
Question 220481: 3x+9y=-7
Answer by Alan3354(5863) (Show Source):
Question 220356: what do you need to do in oreder to solve a proof
Answer by chibisan(120) (Show Source):
Question 219819: Moody wants to find the height of the tallest building in his city. He stands 332 feet away from the building. There is a tree 34 feet in front of him, which he knows is 20 feet tall. How tall is the building to the nearest foot?
Answer by checkley77(6671) (Show Source):
Question 219394: write a two-column proof
given <1 and <2 form a linear pair
<2 and <3 are supplementary
proven <1=<3
Answer by susanaramya(9) (Show Source):
Question 219099: finding angle measures
Answer by solver91311(4818) (Show Source):
Question 218341: What is the side splitting theorem proof?
Answer by solver91311(4818) (Show Source):
You can put this solution on YOUR website!
If a line is constructed parallel to one side of a triangle that intersects the other two sides in distinct points, then the other two sides each form a transversal where the corresponding angles are equal. Since you now have two triangles with two pairs of angles equal because of equal corresponding angles of a transversal and the third angle is in common, you have two triangles that have all three angles congruent. Since all three angles are congruent, the triangles must be similar (AAA). Since the triangles are similar, their corresponding sides are in proportion by definition of similarity.
John
Question 216778: If two points are noncollinear, then a right triangle contains one obtuse angle? true or false? and why would it be false?
Answer by Alan3354(5863) (Show Source):
You can put this solution on YOUR website!If two points are noncollinear, then a right triangle contains one obtuse angle? true or false? and why would it be false?
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False. A right triangle never has an obtuse angle.
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One angle of a right triangle is 90 degs.
SincetThe other 2 total 90 degrees, both have to be less than 90 degs.
Question 216261: What is a counterexample for the following statement? If a number is real then it is irrational.
Answer by vleith(1925) (Show Source):
Question 216032: I really need help with these!! I cannot find the indicated angle measurements for the angles.
Answer by stanbon(25959) (Show Source):
You can put this solution on YOUR website!x=?, m
The question says to find the value of x and the measure of each angle in the triangle. There is a scalene triangle, where point A is at the top and it says that A represents (30x)degrees, B says (40x)degrees, and C represents (10x)squared. My teacher said to use to use factoring or the quadratic formula. The lesson is "The Triangle Sum Theroem". Thank you so much for your time. I just cannot do these!!
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Equation:
A + B + C = 180 degrees
30x + 40x + (10x)^2 = 180
70x + 100x^2 = 180
---
100x^2 + 70x - 180 = 0
Divide thru by 10 to get:
10x^2 + 7x - 18 = 0
---
Use the quadratic formula to get:
x = [-7 +- sqrt(49 - 4*10*-18)]/20
x = [-7 +- 27.73]/20
Positive solution:
x = 20.73/20
x = 1.04
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mA = 30*1.04 = 31.1 degrees
mB = 40*1.04 = 41.6 degrees
mC = (10x)^2 = 10.4*2 = 108.16 degrees
====================================
Cheers,
Stan H.
What angles?
Cheers,
Stan H.
Question 216014: On a formal proof how do I choose which statement to write first. (besides the given)
Answer by vleith(1925) (Show Source):
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Older solutions: 1..45, 46..90, 91..135, 136..180, 181..225, 226..270, 271..315, 316..360, 361..405, 406..450, 451..495, 496..540, 541..585
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