Question Bank - P2 — Maths STD 10 — Question

$\therefore \angle A=\angle C \quad \ldots . . .[\text { Isosceles triangle theorem }]$

$\text { Let } \angle A=\angle C=x$

$\text { In } \triangle A B C$

$\angle A+\angle B+\angle C=180^{\circ}\ldots\left[\text { Sum of the measures of the angles of a triangle is } 180^{\circ}\right]$

$\therefore x+90^{\circ}+x=180^{\circ}$

$\therefore 2 x=90^{\circ}$

$\therefore x=\frac{90^{\circ}}{2}$

$\therefore x=45^{\circ}$

$\therefore m \angle A=45^{\circ}$