Question

Please help for 50 points

Answer 1

Answer:

A

Step-by-step explanation:

The exterior angle is equal to the sum of the opposite interior angles.

Call the inside angle D

A+ B + D = 180   sum of the angles of a triangle is 180

C+D = 180 since the form a straight line

Solving for D

D = 180-C

Substitute this into the first equation

A+ B + 180-C = 180

Subtract 180 from each side

A+ B + -C =0

Add C to each side

A + B = C

This proves the theorem

Answer 2

Answer:

A

Step-by-step explanation:

An exterior angle = sum of other two interior angles (at other vertices)