Question

The given triangle is right angled at B. Find m∠A.

• A. ${45}^{\circ }$
• B. ${35}^{\circ }$
• C. ${60}^{\circ }$
• D. ${55}^{\circ }$

Answer 1

The correct option is D ${55}^{\circ }$

Angle sum property: The sum of the three interior angles of a triangle is 180°.

Given,
Triangle ABC is right angled at B. Therefore,
m∠B = 90°

In triangle ABC,
m∠C = 35°
m∠B = 90°

So,
m∠A + m∠B + m∠C = 180°

∴ m∠C + m∠B = 90° + 35° = 125°

$\text{Third angle}$ = 180° – 125° = 55°

∴ m∠A = 55°