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iamsmooth
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Homework Statement
Determine all points on the function [itex]y=\sin2x-2sinx[/itex] where the tangent is parallel to the x-axis.
Homework Equations
f'(sin(x)) = cos(x)
chain rule:
f'(f(g(x)) = g'f + f'g
The Attempt at a Solution
[tex]y=sin2x-2sinx[/tex]
[tex]y\prime=cos(2x)(2)-[2cosx+0sinx][/tex]
[tex]y\prime=cos(2x)(2)-2cosx[/tex]
If I multiply 2 and cos(2x), do I get 2cos(2x) or do I get 2cos(4x)?
Is there a way to simplify it further by subtracting the -2cosx?
Do I use the sum and difference identities? My trig is still pretty rusty :(
In a similar question without trig, we'd derive the equation, and factor it to find out the points of x; but I'm not quite sure how to do this :(
Thanks for the help.
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