If sin A + sin square A=1 and a cos 12 A + b cos I 0 A + c cos 8A + d cos 6 A =1 then find a+b+c+d upon 8abcd

Answer 1

(a+b+c+d)/8abcd = (1+3+3+1)/8x1x3x3x1) , the answer: 1/9