Question

Cynthia is writing a proof of the theorem stated below.

Theorem: The sum of interior angles of a triangle is 180°.

She first drew the figure shown below.
Which theorem will she most likely use in the proof?
Answer

Vertical angles are congruent.

If two angles form a straight angle, then they are supplementary.

Alternate Interior Angles formed by parallel lines and their transversal are complementary.

Corresponding angles formed by parallel lines and their transversal are supplementary.

Answer 1

My guess would be "If two angles form a straight angle, then they are supplementary."
We can see that in the bottom right of the figure she has demonstrated that angles 1+2+3 form a straight angle. As such, the case can be made that angle UQR + 3 forms a straight angle, so UQR + 3 = 180. But UQR = 1+2, so 1+2+3 = 180.

Answer 2

gottt itt thank-you =)

Answer 3

so whats the answer

Answer 4

for real...