- #1
Hockeystar
- 64
- 0
Homework Statement
Find the max/min of the function for [0,pi/2]
f(x)= kcos2xsin(x)
Homework Equations
Product Rule and chain rule
The Attempt at a Solution
f'(x)= k(2cosx(-sinx)(sinx)+cos2xcosx)
f'(x)= kcosx(-2sin2x+cos2x)
Set eqaution to 0
(2sin2x+cos(x)2) = 0
2(1-cos2x)+cos(x)2 = 0
cos2x = 2
?
Now I'm stuck. There should be a max or min.