If $\"\"$ and $\"\"$ are the two complementary angles, then $\"\"$ .

Now prove that $\"\"$ .

Consider left hand side of the equation $\"\"$ .

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

Co-function identity : $\"\"$ .

$\"\"$

Pythagorean identity : $\"\"$ .

$\"\"$

= Right hand side of the equation.

If $\"\"$ and $\"\"$ are the two complementary angles, then $\"\"$ .