Question

explain or show work on how you can use the triangle sum theorem and/or the exterior angle theorem to find the measure of angle a.

Explanation:

Step1: Recall Exterior Angle Theorem

The exterior - angle of a triangle is equal to the sum of the two non - adjacent interior angles.

Step2: Identify non - adjacent interior angles

The non - adjacent interior angles to angle $a$ are $55^{\circ}$ and $65^{\circ}$.

Step3: Calculate angle $a$

$a=55 + 65$

Answer:

$a = 120^{\circ}$