$\"\"$

The trigonometric function is $\"\"$ , where $\"\"$ lies in quadrant III.

Definition of trigonometric function $\"\"$ .

Opposite side = $\"\"$ and adjacent side = $\"\"$ .

Pythagorean theorem :

For right angled triangle, square of Hypotenuse is equal to sum of squares of other two sides. $\"\"$ .

Substitute the values of opposite side = $\"\"$ and adjacent side = $\"\"$ in above equation.

$\"\"$

$\"\"$ .

As $\"\"$ lies in quadrant III, the value of secant function is negative.

$\"\"$ . $\"\"$

The value of $\"\"$ .