If $\sin x=-\frac{2 \sqrt{6}}{5}$and $x$ lies in Quadrant III, find the values of $\cos x$ and $\cot x$.
Given: $\sin x=-\frac{2 \sqrt{6}}{5}$
To find: cos x and cot x
Since, $x$ is in IIIrd Quadrant. So, sin and cos will be negative but tan will be positive.
We know that,
$\sin ^{2} x+\cos ^{2} x=1$
Putting the values, we get
$\left(-\frac{2 \sqrt{6}}{5}\right)^{2}+\cos ^{2} x=1$ [Given]
$\Rightarrow \frac{24}{25}+\cos ^{2} x=1$
$\Rightarrow \cos ^{2} x=1-\frac{24}{25}$
$\Rightarrow \cos ^{2} x=\frac{25-24}{25}$
$\Rightarrow \cos ^{2} x=\frac{1}{25}$
$\Rightarrow \cos x=\sqrt{\frac{1}{25}}$
$\Rightarrow \cos x=\pm \frac{1}{5}$
Since, $x$ in IIIrd quadrant and $\cos x$ is negative in IIIrd quadrant
$\therefore \cos x=-\frac{1}{5}$
Now
$\tan x=\frac{\sin x}{\cos x}$
Putting the values, we get
$\tan x=\frac{-\frac{2 \sqrt{6}}{5}}{-\frac{1}{5}}$
$=-\frac{2 \sqrt{6}}{5} \times(-5)$
$=2 \sqrt{6}$
Now,
$\cot x=\frac{1}{\tan x}$
Putting the values, we get
$\cot x=\frac{1}{2 \sqrt{6}}$
Hence, the values of other trigonometric Functions are: