(sinθ)^4+(cosθ)^2+(sinθ)^2(cosθ)^2
=((1-cos2θ)/2)^2+(cosθ)^2+(sin2θ/2)^2
=1/4-cos2θ/2+cos(2θ)^2/4+(1+cos2θ)/2+(sin2θ)^2/4
=1/4+1/4+1/2=1