Question

Jamie is writing a proof of the theorem stated below.

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

He first drew the figure shown below.

Which theorem will he most likely use in the proof?
Supplements of congruent angles are congruent.

Vertical angles are congruent.

Alternate interior angles formed by parallel lines and their transversal are congruent.

If two angles of a triangle are congruent, the sides opposite these are congruent.

Answer 1

the proof would start with all angles along a line are supplementary. thus, sum of angles 1,2 and 3 is 180.
Then using "Alternate interior angles formed by parallel lines and their transversal are congruent." it can be proved that the angles of the triangle are indeed equal to angles 1,2 and 3

Answer 2

Thaank yoooou(:

Answer 3

Its been a pleasure :)