CUET Preparation Today
CUET
-- Mathematics - Section A
Continuity and Differentiability
If x = 2 cos t – cos 2t and y = 2 sin t – sin 2t then the value of d2ydx2 at =π2 is : |
3/2 -5/2 5/2 -3/2 |
-3/2 |
dxdt=−2sint+2sin2t dydt=2cost−2cos2t dydt=2cost−2cos2t−2sint+2sin2t=cost−cos2tsin2t−sint =2sin3t2sint22cos3t2sint2=tan3t2 d2ydx2=sec23t2×32×dtdx =32sec23t2.12sin2t−2sint ⇒d2ydx2|t=π2=−32 Hence (4) is correct answer. |