Prove the following identities, where the angles involved are acute angles for which the expressions are defined.
$\sqrt{\frac{1+\sin A }{1-\sin A }}=\sec A +\tan A$
$\sqrt{\frac{1+\sin A }{1-\sin A }}=\sec A +\tan A$
$L.H.S.=\sqrt{\frac{1+\sin A }{1-\sin A }}$
$=\sqrt{\frac{(1+\sin A )(1+\sin A )}{(1-\sin A )(1+\sin A )}}$
$=\frac{(1+\sin A )}{\sqrt{1-\sin ^{2} A }}=\frac{1+\sin A }{\sqrt{\cos ^{2} A }}$
$=\frac{1+\sin A }{\cos A } \quad=\sec A +\tan A$
$= R . H.S.$
$\frac{2 \tan 30^{\circ}}{1-\tan ^{2} 30^{\circ}}=$
Evaluate the following:
$\frac{\sin 30^{\circ}+\tan 45^{\circ}-\operatorname{cosec} 60^{\circ}}{\sec 30^{\circ}+\cos 60^{\circ}+\cot 45^{\circ}}$
Express $\sin 67^{\circ}+\cos 75^{\circ}$ in terms of trigonometric ratios of angles between $0^{\circ}$ and $45^{\circ}$
Show that:
$(i)$ $\tan 48^{\circ} \tan 23^{\circ} \tan 42^{\circ} \tan 67^{\circ}=1$
$(ii)$ $\cos 38^{\circ} \cos 52^{\circ}-\sin 38^{\circ} \sin 52^{\circ}=0$
Given $\sec \theta=\frac{13}{12},$ calculate all other trigonometric ratios.