$\"\"$

The equation is $\"\"$ .

Prove that, the equation $\"\"$ is symmetric about the polar axis.

Consider $\"\"$ .

Substiute $\"\"$ for $\"\"$ .

$\"\"$

$\"\"$ is in the form of $\"\"$ .

From the sine difference identity : $\"\"$ .

$\"\"$

Since this substitution produces an equivalent equation $\"\"$ is symmetric with

respective to the polar axis.

$\"\"$

The equation $\"\"$ is symmetric about the polar axis.