Givene(sin2x+sin2x+sin6x......∞)loge2=elog2(11−sin2x)=2(11−2sin2x)=2sec2x=yNow,y2−5y+4=0⇒y2−4y−y+4=0⇒y(y−4)−1(y−4)=0⇒(y−4)(y−1)=0∴y=4andy=1If2sec2x=1sec2x=0(notpossibleassecx≥1)else,2sec2x=4sec2x=2cosx=1√2Thus,thevalueofsinxcosx−sinx=1√21√2−1√2⇒Notdefined.