Question

In a triangle, if sum of two angles is equal to the third angle (considering the interior angles only), then the triangle is

• A. Right-angled
• B. Acute-angled
• C. Equilateral
• D. Obtuse-angled

Answer 1

The correct option is A Right-angled

Let in a triangle $ABC$,the sum of two angles is equal to the third angle.

i.e. $\angle A=\angle B+\angle C$ ....(1)

We know $\angle A+\angle B+\angle C={180}^0$

$\Rightarrow \angle A+\angle A={180}^0$ ....From (1)

$\Rightarrow 2\angle A={180}^0$

$\Rightarrow \angle A={190}^0$ (Right angle)

Hence, triangle $ABC$ is a right-angled triangle.