Question

1. ∠7 is a supplement of ∠8, and ( mangle7 = 109^circ ). find ( angle8 ).

Explanation:

Step1: Recall supplement definition

Supplementary angles sum to $180^\circ$, so $m\angle7 + m\angle8 = 180^\circ$.

Step2: Substitute known angle value

Substitute $m\angle7 = 109^\circ$: $109^\circ + m\angle8 = 180^\circ$.

Step3: Solve for $m\angle8$

Rearrange to isolate $m\angle8$: $m\angle8 = 180^\circ - 109^\circ$.

Answer:

$71^\circ$