Question

Given the diagram below, Gitta writes m1 + m2 + m3 = 180degrees. Which of the following reasons allows her to write this statement?

A. Triangle sum theorem
B. Subtraction property of equality
C. Definition of linear pair
D. Exterior angles theorem

Answer 1

I believe the answer is A.

Answer 2

A. Triangle sum theorem.

Explanation:

We have been given that
`m\angle 1+m\angle 2+m\angle 3=180^(\circ)`.

We know that angle sum property of triangle states that three angles of a triangle add up-to 180 degrees.

Since the sum of angles of a triangle is 180 degrees, therefore, option A is the correct choice.