Question

find m∠qrs.

Explanation:

Step1: Identify isosceles triangle

Since $QR = RS$, $\triangle QRS$ is isosceles. So $\angle Q=\angle S = 42^{\circ}$.

Step2: Use angle - sum property of triangle

The sum of interior angles of a triangle is $180^{\circ}$. Let $\angle QRS=x$. Then $x + 42^{\circ}+42^{\circ}=180^{\circ}$.

Step3: Solve for $\angle QRS$

$x=180^{\circ}-(42^{\circ}+42^{\circ})=180^{\circ}-84^{\circ}=96^{\circ}$.

Answer:

$96^{\circ}$