Question

1. find m∠1. 38° 42° 78° 52°

Explanation:

Step1: Recall triangle - angle sum property

The sum of the interior angles of a triangle is 180°. In a right - triangle, one angle is 90°. Let the given non - right angle be 38°.

Step2: Calculate the unknown angle

Let the unknown angle be $\angle1$. We use the formula $\angle1=180^{\circ}-90^{\circ}-38^{\circ}$.
$180 - 90-38=52^{\circ}$

Answer:

$52^{\circ}$