Question

$\mathbf{\sin}\mathbf{1}\mathbf{6}\mathbf{3}^{\mathbf{o}}\mathbf{\cos}\mathbf{3}\mathbf{4}\mathbf{7}^{\mathbf{o}}\mathbf{+}\mathbf{\sin}\mathbf{7}\mathbf{3}^{\mathbf{o}}\mathbf{\sin}\mathbf{1}\mathbf{6}\mathbf{7}^{\mathbf{o}}\mathbf{=}$

• A. 0
• B. $1/2$
• C. 1
• D. None of these

Answer 1

Answer: (B)

$1/2$

Answer 2

$\sin(90^{o} + 73^{o}).\cos(360^{o} - 13^{o}) + \sin 73^{o}.\sin(180^{o} - 13^{o})$ =$\cos 73^{o}.\cos 13^{o} + \sin 73^{o}.\sin 13^{o}$

$= \cos(73^{o} - 13^{o}) = \cos 60^{o} = \frac{1}{2}$.