Question

In a right-angled triangle $ABC$ with $\angle C={90}^o$ and $\angle A=2\angle B,\angle B$ is

• A. ${15}^o$
• B. ${60}^o$
• C. ${45}^o$
• D. ${30}^o$

Answer 1

The correct option is D ${30}^o$

$\angle C={90}^{o}or\angle A+\angle B={90}^o$
$But2\angle B+\angle B={90}^o$
$\therefore \angle B={30}^o$