1. ## Derivatives

Using the derivative or graph of the chosen pair of frequencies (in this case f1=10 , f2=8) determine 3 occasions (values of x) when it is stationary(not moving).

So derivative is -18cos(x)sin(9x)-2sin(x)cos(9x)
2nd derivative is (if any help) 36sin(x)sin(9x)-164cos(x)cos(9x)

graph of function will be attached.

then verify that the times are accurate by making appropriate substitutions and calculations.

plz help and explain steps done.

2. Originally Posted by Buzzins
Using the derivative or graph of the chosen pair of frequencies (in this case f1=10 , f2=8) determine 3 occasions (values of x) when it is stationary(not moving).

So derivative is -18cos(x)sin(9x)-2sin(x)cos(9x)
2nd derivative is (if any help) 36sin(x)sin(9x)-164cos(x)cos(9x)

graph of function will be attached.

then verify that the times are accurate by making appropriate substitutions and calculations.

plz help and explain steps done.
By definition, a stationary point is a point at which the derivative is zero. Set the derivative to zero and solve for x.