If  6cos2θ+2cos2θ/2+2sin2θ=0 where −π<0<π , then  θ is equal to

The given equation can be written as62cos2θ−1+1+cosθ+21−cos2θ=0⇒10cos2θ+cosθ−3=0⇒5cosθ+32cosθ−1=0⇒cosθ=12  or  ⇒cosθ=-35⇒θ=π3  or   θ=π−cos−135 as −π<θ<π⇒θ=π3,π−cos−135