$\"\"$

From the diagram opposite side = 15, adjacent side = 21 and the angle $\"\"$ .

The measure of the adjacent side is 21 and opposite side = 15.

The trigonometric function relating the adjacent side of a right triangle and

the opposite side is the tangent function.

$\"\"$ (Apply Tangent ratio)

$\"\"$ (Substitute opposite side = 15 and adjacent side = 21)

$\"\"$

$\"\"$ (Use calculator) $\"\"$

The value of $\"\"$ .