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sandy524
 3 years ago
find the derivative of f(x) = cos(x) − sin^2(x) on [0,2pi]
sandy524
 3 years ago
find the derivative of f(x) = cos(x) − sin^2(x) on [0,2pi]

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sandy524
 3 years ago
Best ResponseYou've already chosen the best response.0i now know that its sin(x)(2cos(x)+1)

sandy524
 3 years ago
Best ResponseYou've already chosen the best response.0can yu guys help me find the critical points

myininaya
 3 years ago
Best ResponseYou've already chosen the best response.0Are you sure it ask you to find f'(x) on [a,b]?

myininaya
 3 years ago
Best ResponseYou've already chosen the best response.0If so, you did that. You are done.

sandy524
 3 years ago
Best ResponseYou've already chosen the best response.0yes. may you help me find the critical points of this now

myininaya
 3 years ago
Best ResponseYou've already chosen the best response.0Set f'(x)=0 and solve for x to find the critical numbers.

myininaya
 3 years ago
Best ResponseYou've already chosen the best response.0You only need to solve this on the interval [0,2 pi]

sandy524
 3 years ago
Best ResponseYou've already chosen the best response.0can we do it together please

myininaya
 3 years ago
Best ResponseYou've already chosen the best response.0You are already factored f'(x) Now set both factors equal to 0.

sandy524
 3 years ago
Best ResponseYou've already chosen the best response.0how? can we work out the problem

myininaya
 3 years ago
Best ResponseYou've already chosen the best response.0Yes. I'm walking you through it. You have sin(x)*(1+2cos(x))=0 Set both factors equal to 0.

myininaya
 3 years ago
Best ResponseYou've already chosen the best response.0Just like if you have a*b=0 then either a=0 or b=0 or both=0

sandy524
 3 years ago
Best ResponseYou've already chosen the best response.0http://www.wolframalpha.com/input/?i=sin%28x%29%282cos%28x%29%2B1%29%3D0

sandy524
 3 years ago
Best ResponseYou've already chosen the best response.0im confused about the results

myininaya
 3 years ago
Best ResponseYou've already chosen the best response.0Use your unit circle. Keep in mind you only have to look between 0 and 2pi

myininaya
 3 years ago
Best ResponseYou've already chosen the best response.0You have sin(x)=0 or 1+2cos(x)=0 Solve both of these for the trig function. Solve the first one for sin(x) and solve the second one for cos(x). Tell me what you get after doing this.

myininaya
 3 years ago
Best ResponseYou've already chosen the best response.0Well you are trying to solve sin(x)=0 for x. You could divide both sides by 1 since 1 will never be 0. Try solving this: sin(x)=0 Then we will come back to 1+2cos(x)=0
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