# What is the parametric equation of ellipse ?

## Solution :

The equation x = acos$$\theta$$ & y = bsin$$\theta$$ together represent the parametric equation of ellipse $${x_1}^2\over a^2$$ + $${y_1}^2\over b^2$$ = 1, where $$\theta$$ is a parameter.

Note that if P($$\theta$$) = (acos$$\theta$$, bsin$$\theta$$) is on the ellipse then ; Q($$\theta$$) = (acos$$\theta$$, bsin$$\theta$$) is on auxilliary circle.

A circle described on major axis as diameter is called auxilliary circle.