Question

find m∠mon. answer attempt 1 out of 2 m∠mon =

Explanation:

Step1: Identify isosceles - triangle

Since two sides of the triangle are equal (the marks on the sides), $\triangle MON$ is an isosceles triangle. In an isosceles triangle, the base - angles are equal. So, $\angle M=\angle N = 57^{\circ}$.

Step2: Use angle - sum property of a triangle

The sum of the interior angles of a triangle is $180^{\circ}$. Let $\angle MON=x$. Then $x + 57^{\circ}+57^{\circ}=180^{\circ}$.

Step3: Solve for $\angle MON$

$x=180^{\circ}-(57^{\circ}+57^{\circ})=180^{\circ}-114^{\circ}=66^{\circ}$.

Answer:

$66$