Question

9 find the measure of the \?\ or \x\. ?=

Explanation:

Step1: Recognize the triangle type

This is an isosceles triangle (marked with equal - side symbols), so the base angles are equal. One base angle is \(55^{\circ}\), so the other base angle is also \(55^{\circ}\).

Step2: Use the triangle - angle - sum formula

The sum of the interior angles of a triangle is \(180^{\circ}\). Let \(x\) be the unknown angle. Then \(x + 55^{\circ}+55^{\circ}=180^{\circ}\).

$$x=180^{\circ}-(55^{\circ} + 55^{\circ})$$

$$x=180^{\circ}-110^{\circ}$$

Answer:

\(70^{\circ}\)