# Thread: Finding the measures of a Triangle

1. ## Finding the measures of a Triangle

Hey Guys!

For number 39, I do not understand how to get answers B and C. I understand that for angle T, B = 20. Since both sides are congruent, the angles opposite these sides are also congruent. Now angle T = 80 because 80+80 = 160 + 20 = 180.
I do not understand how part B is 100 and part C is 40. Can somebody clarify these for me? Thanks.

2. ## Re: Finding the measures of a Triangle

Originally Posted by Cake
Hey Guys!

For number 39, I do not understand how to get answers B and C. I understand that for angle T, B = 20. Since both sides are congruent, the angles opposite these sides are also congruent. Now angle T = 80 because 80+80 = 160 + 20 = 180.
I do not understand how part B is 100 and part C is 40. Can somebody clarify these for me? Thanks.
1. Your considerations and calculations are OK so far.

2. The straight line AT forms an angle of 180° at R. Since angle T = angle R the angle $|\angle(ARB)|=180^\circ-80^\circ$

3. The triangle $\Delta(BRA)$ is isosceles that means the angles $\angle(RBA)$ and $\angle(BAR)$ are have the same measure.

3. ## Re: Finding the measures of a Triangle

Hi,
I hope you can follow the calculations in the attachment: