Question

1. find the measure of the missing angle ∠a in the triangle below. 25° 20° 10° 15°

Explanation:

Step1: Recall angle - sum property

The sum of interior angles of a triangle is 180°. Let the missing angle be $\angle A$. We know two angles: 60° and 105°.

Step2: Set up the equation

$\angle A+60^{\circ}+105^{\circ}=180^{\circ}$.

Step3: Solve for $\angle A$

$\angle A = 180^{\circ}-(60^{\circ}+105^{\circ})=180^{\circ}-165^{\circ}=15^{\circ}$.

Answer:

15°