Find , when

Theorem: y and x are given in a different variable that is θ . We can find by finding and and then dividing them to get the required thing.

=

= a× 3 sin²θ × cosθ (using the chain rule = 3sin²θ× = 2sin²θ × cosθ )

= 3asin²θcosθ . ………..(1)

= a × (3cos²θ)× (-sinθ ) (using chain rule = 2cosθ× = 2 cosθ × (-sinθ ) )

= -3asinθcos²θ.

Dividing (1) and (2), we get

=

= .

= -tanθ