Express the trigonometric ratios $\sin A , \sec A$ and $\tan A$ in terms of $\cot A$.
We know that,
$\operatorname{cosec}^{2} A=1+\cot ^{2} A$
$\frac{1}{\operatorname{cosec}^{2} A}=\frac{1}{1+\cot ^{2} A}$
$\sin ^{2} A=\frac{1}{1+\cot ^{2} A}$
$\sin A=\pm \frac{1}{\sqrt{1+\cot ^{2} A}}$
$\sqrt{1+\cot ^{2} A}$ will always be positive as we are adding two positive quantities.
Therefore, $\sin A =\frac{1}{\sqrt{1+\cot ^{2} A }}$
We know that, $\tan A =\frac{\sin A }{\cos A }$
However, $\cot A=\frac{\cos A}{\sin A}$
Therefore, $\tan A =\frac{1}{\cot A }$
Also, $\sec ^{2} A=1+\tan ^{2} A$
$=1+\frac{1}{\cot ^{2} A}$
$=\frac{\cot ^{2} A+1}{\cot ^{2} A}$
$\sec A=\frac{\sqrt{\cot ^{2} A+1}}{\cot A}$
Evaluate:
$\cos 48^{\circ}-\sin 42^{\circ}$
Evaluate $\frac{\tan 65^{\circ}}{\cot 25^{\circ}}$
If $\sec 4 A =\operatorname{cosec}\left( A -20^{\circ}\right),$ where $4 A$ is an acute angle, find the value of $A$. (in $^{\circ}$)
Prove the following identities, where the angles involved are acute angles for which the expressions are defined.
$\left(\frac{1+\tan ^{2} A}{1+\cot ^{2} A}\right)=\left(\frac{1-\tan A}{1-\cot A}\right)^{2}=\tan ^{2} A$
Prove the following identities, where the angles involved are acute angles for which the expressions are defined.
$\frac{\tan \theta}{1-\cot \theta}+\frac{\cot \theta}{1-\tan \theta}=1+\sec \theta \operatorname{cosec} \theta$