Solution :
Time taken to reach the extreme position from equilibrium position is $ \large\frac{T}{4}$
Velocity is maximum at equilibrium position and zero at extreme position.
$v= A \omega \cos \omega mv^2$
$K.E = \large\frac{1}{2} $$mv^2$
(m is the mass of particle and v is the velocity of particle)
$K.E= \large\frac{1}{2}$$mA^2 \omega ^2 \cos ^2 \omega t$
Hence graph of K.E. v/s time is square cos function