If cos(x2)cos(x22)cos(x23)...............to ∞=sin xxthen 122sec2(x2)124sec2(x22)+.......=
log cosx2+log cosx22+......log sin x−log x⇒−12 tanx2−122tanx22...=cot x−1x⇒122 sec2x2+124sec2x22+...=cox ec2x−1x2