HINT: Eventually you will need to factor. Just before factoring, try multiplying both sides of the equation by 2 to get rid of the fraction. Solution cot^2 theta=(3/2)csc theta cot theta=cos theta/sin theta and csc theta=1/sin theta cos^2 theta/sin^2 theta= (3/2sin theta) 2 cos ^2 theta= 3sin theta and cos^2 theta= 1- sin^2 theta 2(1-sin^2 theta)= 3 sin theta 2-2sin^2 theta= 3sin theta 2sin^2 theta -3sin theta -2=0 (sin theta -2)(2sin theta +1)=0 sin theta=2 and sin theta=-1/2 we have to ignore sin theta=2 since sin theta lies between -1 and 1 therefore sin theta=-1/2 theta= 7pi/ 6 , 11pi/6.