This post is about derivatives of Polar and parametric Equations. Because of polar equation, Polar equation like parametric equations of the curve where the angle θ is parameter. As well as equations have parameter (r,θ).
For this polar equation, the parametric equations are x ( θ) = cos θ and y ( θ) = sin θ. Therefore, the derivative is which matches what we got for the parametric derivative of a circle.
Reviewsheet-A polar and parametric