Express the trigonometric ratios $\sin A , \sec A$ and $\tan A$ in terms of $\cot A$.

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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, $\sec ^{2} A=1+\tan ^{2} A$

$=1+\frac{1}{\cot ^{2} A}$

$=\frac{\cot ^{2} A+1}{\cot ^{2} A}$

$\sec A=\frac{\sqrt{\cot ^{2} A+1}}{\cot A}$

Similar Questions

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.

$\frac{\tan \theta}{1-\cot \theta}+\frac{\cot \theta}{1-\tan \theta}=1+\sec \theta \operatorname{cosec} \theta$