Question

what is m∠1? m∠1 =

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 two non - adjacent interior angles to $\angle1$ are $51^{\circ}$ and $77^{\circ}$.

Step3: Calculate $\angle1$

$m\angle1=51^{\circ}+77^{\circ}$

Answer:

$128$