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

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

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

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

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

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

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

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

sandy524 Group TitleBest ResponseYou've already chosen the best response.0
can we do it together please
 2 years ago

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

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

sandy524 Group TitleBest ResponseYou've already chosen the best response.0
step by step please
 2 years ago

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

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

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

sandy524 Group TitleBest ResponseYou've already chosen the best response.0
this is all i have
 2 years ago

sandy524 Group TitleBest ResponseYou've already chosen the best response.0
im confused about the results
 2 years ago

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

myininaya Group TitleBest ResponseYou've already chosen the best response.0
You 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.
 2 years ago

myininaya Group TitleBest ResponseYou've already chosen the best response.0
Well 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
 2 years ago
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