If \(\sin x \cos h y=\cos \theta, \cos x \sin h y=\sin \theta\) and \(4 \tan x=3\). Then, \(\sin h^2 y=\)

If \(\sin x \cos h y=\cos \theta, \cos x \sin h y=\sin \theta\) and \(4 \tan x=3\). Then, \(\sin h^2 y=\)
  1. \(\frac{4}{5}\)
  2. \(\frac{9}{16}\)
  3. \(\frac{9}{25}\)
  4. \(\frac{16}{25}\)

Solution

\(\begin{aligned} & \text {Since, } \tan x=\frac{3}{4} \\ & \Rightarrow \quad \sin ^2 x=\frac{9}{25} \\ & \text { and } \quad \cos ^2 x=\frac{16}{25} \\ & \text { and } \sin x \cosh y=\cos \theta, \cos x \sinh y=\sin \theta \\ & \because \cos ^2 \theta+\sin ^2 \theta=1 \\ & \Rightarrow(\sin x \cosh y)^2+(\cos x \sinh y)^2=1 \\ & \Rightarrow \frac{9}{25}\left(1+\sinh ^2 y\right)+\frac{16}{25} \sinh ^2 y=1 \\ & \Rightarrow 9+9 \sinh ^2 y+16 \sinh ^2 y=25 \end{aligned}\) \(\Rightarrow \sinh ^2 y=\frac{16}{25}\) Hence, option (4) is correct.

Asked in: AP EAMCET 2019 (20 Apr Shift 1)

Practice more Inverse Trigonometric Functions questions on Aicharya