Question

Question 2 (iii)
Choose the correct option and justify your choice.
(iii) $sin2A$ = 2sinA is true when A =
(A) $0^{\circ }$
(B) ${30}^{\circ }$
(C) ${45}^{\circ }$
(D) ${60}^{\circ }$

Answer 1

Option (A) is correct.
sin 2A = 2 sin A is true when A = 0${}^{\circ }$
As sin 2A = sin $0^{\circ }$ = 0
2 sin A = 2sin $0^{\circ }$ = 2$\times$0 = 0
Another Method
sin 2A = 2sin A cos A
$\Rightarrow$2sin A cos A =2 sin A
$\Rightarrow$ cos A = 1
$\Rightarrow$ A = $0^{\circ }$