Question #0d91d

2 Answers
Jun 17, 2016

y=(34)(2x2).

Explanation:

Recall the identity : sin2θ=1cos2θ2.

Hence,
y=3sin2θ=(32)(1cos2θ)...............(1)

But, it is given that x=2cos2θ,
so that x22=cos2θ.

Now, putting this value of cos2θ in (1), we get,

y=(32)(1x22)=(34)(2x2).

Jun 17, 2016

y=x222

Explanation:

y=3sin2θ
x=2cos2θ
x2=2cos2θ
=2cos2θ2sin2θ
=2cos2θ23y
=2(113y)23y
=243y
so
y=34(x22)