Question
Find the value of other five trigonometric function: $\tan x = \frac{{ - 5}}{{12}}$, x lies in second quadrant.

Answer

Here $\tan x = \frac{{ - 5}}{{12}}$
$\cot x = \frac{1}{{\tan x}} = \frac{{ - 12}}{5}$
Now ${\sec ^2}x = 1 + {\tan ^2}x \Rightarrow {\sec ^2}x = 1 + {\left( {\frac{{ - 5}}{{12}}} \right)^2}$$ \Rightarrow {\sec ^2}x = \frac{{169}}{{144}}$
$ \Rightarrow \sec x = \pm \frac{{13}}{{12}}$
But x lies in second quadrant.
$\therefore sex = \frac{{ - 13}}{{12}}$
$\cos x = \frac{1}{{\sec x}} = \frac{{ - 12}}{{13}}$
Also ${\sin ^2}x + {\cos ^2}x = 1 \Rightarrow {\sin ^2}x + {\left( {\frac{{ - 12}}{{13}}} \right)^2} = 1$$ \Rightarrow {\sin ^2}x = 1 - \frac{{144}}{{169}}$
$ \Rightarrow {\sin ^2}x = \frac{{25}}{{169}} \Rightarrow \sin x = \pm \frac{5}{{13}}$
But x lies in second quadrant.
$\therefore \sin x = \frac{5}{{13}}$
$\cos ecx = \frac{1}{{\sin x}} = \frac{{13}}{5}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free