$\"\"$

The rectangular equation is $\"\"$ .

Rewrite the equation: $\"\"$ .

The equation is in the form of standard equation of parabola $\"\"$ .

Here, $\"\"$ and $\"\"$ .

The eccentricity of a parabola is $\"\"$ .

The directrix of vertical parabola is $\"\"$ .

Substitute $\"\"$ and $\"\"$ .

$\"\"$ .

If the directrix is a horizontal line $\"\"$ , then the polar equation of the conic is $\"\"$ .

The directrix is $\"\"$ .

Substitute $\"\"$ and $\"\"$ in $\"\"$ .

$\"\"$

$\"\"$ .

The polar equation is $\"\"$ .

$\"\"$

The polar equation is $\"\"$ .