Question

problem 13: (first taught in lesson 31) from this given statement, select the definition, property, postulate, or theorem that justifies the prove statement. given: △ghk prove: m∠1 = m∠2 + m∠3

Explanation:

In a triangle, the measure of an exterior angle (in this case, $\angle1$) is equal to the sum of the measures of the two non - adjacent interior angles ($\angle2$ and $\angle3$), which is what the Exterior - Angle Theorem states.

Answer:

The Exterior - Angle Theorem