The number of values of `thetain[0,2pi]` that satisfy the equation `sin^2theta-costheta=1/4`

Explanation

Given:
`sin^2theta-costheta=1/4`
`1-cos^2theta-costheta=1/4`
`-cos^2theta-costheta=1/4-1`
`-cos^2theta-costheta=-3/4`
`cos^2theta+costheta=3/4`
`4cos^2theta+4costheta=3`
`4cos^2theta+4costheta-3=0`
`4cos^2theta-2costheta+6costheta-3=0`
`2costheta(2costheta-1)+3(2costheta-1)=0`
`(2costheta-1)(2costheta+3)=0`
`2costheta-1=0`
`2costheta=1`
`costheta=1/2`
`(2costheta+3)=0`
`2costheta=-3`
`costheta=-3/2`
`costheta=1/2` lies in the interval `[0,2pi]`
Value of `theta=2npi pm pi/3`