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b)for w=400 N and µk=.25, calculate F and theta ranging from 0 to 90 in

increments of 10.Graph F versus theta.

c)From the general expression in part (a) calculate the value of theta for which

the value of F, required to maintain constatnt speed, is a minimum.(Hint: At a

point where a function is minimum, what are the first and second derivatives of

the function? Here F is a function of theta.)for the special case of w=400 N and

µk=.25,evaluate this optimal theta and compare your result to the graph you

constructed in part b.

## Homework Equations

i need help with part c

c)From the general expression in part (a) calculate the value of theta for which

the value of F, required to maintain constatnt speed, is a minimum.(Hint: At a

point where a function is minimum, what are the first and second derivatives of

the function? Here F is a function of theta.)for the special case of w=400 N and

µk=.25,evaluate this optimal theta and compare your result to the graph you

constructed in part b.

## The Attempt at a Solution

this is the solution for part a:

F = µk*w / (cos(theta) + µk*sin(theta))

the problem is that i don't know how to get the dervitives in order to solve part c