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Question: If \(\sin B\) =\(\frac{1}{5}\sin(2A + B)\), then \(\frac{\tan(A + B)}{\tan A} =\)...

If sinB\sin B =15sin(2A+B)\frac{1}{5}\sin(2A + B), then tan(A+B)tanA=\frac{\tan(A + B)}{\tan A} =

A

53\frac{5}{3}

B

23\frac{2}{3}

C

32\frac{3}{2}

D

35\frac{3}{5}

Answer

32\frac{3}{2}

Explanation

Solution

sin(2A+B)sinB=51\frac{\sin(2A + B)}{\sin B} = \frac{5}{1} by componendo and Dividendo.

sin(2A+B)+sinBsin(2A+B)sinB=5+151\frac{\sin(2A + B) + \sin B}{\sin(2A + B) - \sin B} = \frac{5 + 1}{5 - 1}

2sin(A+B).cosA2cos(A+B).sinA=64\frac{2\sin(A + B).\cos A}{2\cos(A + B).\sin A} = \frac{6}{4}tan(A+B)tanA=32\frac{\tan(A + B)}{\tan A} = \frac{3}{2}.