$\"\"$

From the diagram opposite side = 20 and the angle $\"\"$ .

Now find the adjacent side of the triangle by using the trigonometric function.

$\"\"$

Substitute $\"\"$ and opposite side = 20 in above function.

$\"\"$

$\"\"$ ( $\"\"$ )

$\"\"$

Multiply each side by x.

$\"\"$

Divide each side by $\"\"$ .

$\"\"$

The value of $\"\"$ .