Question

If $x=$ ${15}^{\circ }$, evaluate : $4\cos 2x\cdot \sin 4x\cdot \tan 3x-1$

Answer 1

Given, $x={15}^{\circ }$
Now,

$4\cos 2x\sin 4x\tan 3x-1$

$=4\left(\cos 30\right)\left(\sin 60\right)\left(\tan 45\right)-1$

$=4\cdot \frac{\sqrt{3}}{2}\cdot \frac{\sqrt{3}}{2}\cdot 1-1$

$=3-1$ $=2$