### Differential calculusEdit

We have the following formulae:

To find the Cartesian slope of the tangent line to a polar curve *r*(θ) at any given point, the curve is first expressed as a system of parametric equations.

Differentiating both equations with respect to θ yields

Dividing the second equation by the first yields the Cartesian slope of the tangent line to the curve at the point (*r*, *r*(θ)):