Question

In isosceles triangle PQR; PQ=QR and $\angle Q={80}^o$, find the value of $\angle R$ in degrees.

Answer 1

Given , PQ = QR
Thus, $\angle QPR=\angle PRQ=x$ (Isosceles triangle Property)
Sum of angles of triangle = 180
$\angle PQR+\angle PRQ+\angle QPR$ = 180
$80+x+x=180$
$2x=100$
$x={50}^{\circ }$
$\angle R={50}^{\circ }$