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× (1+cosθ ) ………..(1)

= asinθ. …………….(2)

Dividing (1) and (2), we get

=

= .

= ( 1+cosθ=2cos²θ/2 and sinθ = 2sin(θ/2)cos(θ/2))

= cot(θ/2)