Math Help - Please solve 6+6costheta=4sin^2theta?

0<= theta < 2pi

Originally Posted by tanasaur
$\sin^2 \theta=1-\cos^2 \theta$
$6+6\cos \theta=4-4\cos^2 \theta$
$2\cos^2 \theta +3\cos \theta+1=0$
substitute : $t=\cos \theta$ and solve quadratic equation .