Question

One of the angle of a triangle is equal to the sum of the other two. Find the measure of this angle.

Answer 1

Let the triangle be $\Delta ABC$ and $\angle B=\angle A+\angle C$

But, sum of angles of triangle $={180}^o$

$\Rightarrow \angle A+\angle B+\angle C={180}^o$

$\Rightarrow \angle B+\angle B={180}^o$

$\Rightarrow \angle B={90}^o$.