Question

In $△ABC$, $AB=AC$ and $\angle A:\angle B=8:5$. The measure of $\angle A$ in degrees is

Answer 1

In $△ABC,AB=BC,$ $\angle ABC=\angle ACB$

(Angles opposite to equal sides are equal)

Hence, ratio of angles will be $\angle A:\angle B:\angle C=8:5:5$
Let the angles be $8x,5x,5x$
Sum of the angles of the triangle = ${180}^o$
$8x+5x+5x=180$
$18x=180$
$x=10$
Thus, $\angle A={80}^{\circ }$