Question

what is ( mangle1 )?
( mangle1=square^{circ} )

Explanation:

Step1: Find the third angle of the triangle

The sum of the interior angles of a triangle is \(180^\circ\). So the third angle \(x\) inside the triangle is \(180^\circ - 38^\circ - 40^\circ\).

$$ x = 180 - 38 - 40 = 102^\circ $$

Step2: Find \(m\angle1\)

\(\angle1\) and the third angle of the triangle are supplementary (they form a linear pair), so their sum is \(180^\circ\). Let \(m\angle1 = y\), then \(y + 102^\circ = 180^\circ\).

$$ y = 180 - 102 = 78^\circ $$

Answer:

\(78\)