Given data:
The maximum height of the toy at t=5 seconds is M= 18 cm.
The minimum height of the toy at t=9 seconds is m=6 cm.
The expression for the amplitude is,
The expression for the mean value is,
The period of the given curve is,
The equation for the given curve is,
Thus, equation of the given curve is y=6 cos(π(t-4)/5)+12.