If x=2cost−cos2t, y=2sint−sin2t , then the value of y2 at t=π2 is
dydx=dydtdxdt=2cost−2cos2t−2sint+2sin2t
=cost−cos2tsin2−sint
d2ydx2=ddt(dydx)dtdx
=(sint+2sin2t)(sin2t−sint)(2cos2t−cost)(cost−cos2t)(sin2t−sint)2(−2sint+2sin2t)
=(−1)(−1)−(−2)(+1)−2
=−32