Question 95

What is the value of $$\frac{3}{2}(\frac{\cos 39}{\sin51})-\sqrt{\sin^2 39+\sin^2 51}=?$$

Solution

Expression : $$\frac{3}{2}(\frac{\cos 39}{\sin51})-\sqrt{\sin^2 39+\sin^2 51}=?$$

= $$\frac{3}{2}(\frac{\cos (90-51)}{\sin51})-\sqrt{\sin^2 (90-51)+\sin^2 51}$$

= $$\frac{3}{2}(\frac{\sin 51}{\sin51})-\sqrt{\cos^2 51+\sin^2 51}$$

= $$\frac{3}{2}-\sqrt1$$

= $$\frac{3}{2}-1=\frac{1}{2}$$

=> Ans - (A)

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