Question

find the missing angle measure.

Explanation:

Step1: Recall angle - sum property of a triangle

The sum of the interior angles of a triangle is 180°.

Step2: Identify known angles

One angle is 40° and another is 90° (right - angled triangle as indicated by the square symbol). Let the missing angle be \(x\).
So, \(40^{\circ}+90^{\circ}+x = 180^{\circ}\).

Step3: Solve for the missing angle

First, simplify the left - hand side: \(130^{\circ}+x = 180^{\circ}\).
Then, subtract 130° from both sides: \(x=180^{\circ}- 130^{\circ}\).
\(x = 50^{\circ}\)

Answer:

\(50^{\circ}\)