How do you find the derivative of P(t) = 3000 + 500 sin(2πt−(π/2))?

1 Answer
Feb 28, 2017

P'(t) = 1000 pisin(2pit)

Explanation:

We have:

P(t) = 3000 + 500 sin(2pit-pi/2)

Which we can rewrite (*) as:

P(t) = 3000 - 500 cos(2pit)

Differentiating wrt t, and applying the chain rile we have:

P'(t) = 0 - 500 * (-sin(2pit)) * 2pi
" " = 1000 pisin(2pit)

Notes (*)

Using the Angle-Sum Identity:

sin(A+-B) -= sinAcosB +- cosAsinB

We can write;

sin(2pit-pi/2) = sin(2pit)cos(pi/2)-cos(2pit)sin(pi/2)
" " = sin(2pit)(0)-cos(2pit)(1)
" " = -cos(2pit)