SOLUTION: Hello First of all in advance I thank you for the help you give me! Okay so here is the problem I am having a hard time with. Instruction: Write a paragraph proof for th

Algebra ->  Geometry-proofs -> SOLUTION: Hello First of all in advance I thank you for the help you give me! Okay so here is the problem I am having a hard time with. Instruction: Write a paragraph proof for th      Log On


   



Question 663230: Hello
First of all in advance I thank you for the help you give me!
Okay so here is the problem I am having a hard time with.
Instruction:
Write a paragraph proof for this form of Theorem 2-2.
If two angles are supplements of congruent angles, then the two angles are congruent.
Given: <1 and <2 are supplementary
<3 and <4 are supplementary
<2 is congruent to <4
Prove: <1 is congruent to <3
What I have:
By the definition of supplementary angles, m<1 + m<2=180 and m<1 + m<4=180. By substitution, m<1 + m<2= m<1 + m<4. Subtract m<1 from each side. You get m<2= m<4, or angle 2 is congruent to angle 4.
That is all I have so far...
However that would only prove...angle 2 is congruent to angle 4...it wouldn't prove what I need to prove...
May you help me?

Found 2 solutions by solver91311, MathLover1:
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


Defn Supplementary

Defn Supplementary

Defn Congruence

Transitive equality

Subtraction property of equality

Defn Congruent: Q.E.D.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism


Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
Proving Theorem 2-1
Given: <1 and <2 are supplementary
<3 and <4 are supplementary
<2 is congruent to <4
Prove: <1 is congruent to <3

Paragraph Proof:

By the Angle Addition Postulate, <1 +<2 = 180 and <3 + <4 = 180.
By substitution, <1 +<2 = <3 + <4.
It is given that <2 is congruent to <4.
By substitution, <1 +<2 = <3 + <2.
Subtract <2 from each side.
You get <1 = <3, or <1 is congruent to <3.