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marasofia1616
 3 years ago
Find all solutions to the equation in the interval [0, 2π).
cos 2x  cos x = 0
marasofia1616
 3 years ago
Find all solutions to the equation in the interval [0, 2π). cos 2x  cos x = 0

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hieuvo
 3 years ago
Best ResponseYou've already chosen the best response.0so, cos2x=cosx, I think x is in those special angles

RadEn
 3 years ago
Best ResponseYou've already chosen the best response.2use identity : cos2x=2cos^2 x  1

RadEn
 3 years ago
Best ResponseYou've already chosen the best response.2so, we have a quadratic equation in form cosx, 2cos^2 x  1  cosx = 0 or 2cos^2 x  cosx  1 = 0 can u factor out it

marasofia1616
 3 years ago
Best ResponseYou've already chosen the best response.0ok I get cos x(2 cos x1)=1

RadEn
 3 years ago
Best ResponseYou've already chosen the best response.2np, it should be (2cosx + 1)(cosx  1) = 0

RadEn
 3 years ago
Best ResponseYou've already chosen the best response.2now, for zeroes take each factors be zero, so 2cosx+1=0 or cosx1=0 solve for x

marasofia1616
 3 years ago
Best ResponseYou've already chosen the best response.0ok I got the solutions 0, 2pi/3 and 4pi/3

RadEn
 3 years ago
Best ResponseYou've already chosen the best response.2looks 0 be same for 2pi, right ?

marasofia1616
 3 years ago
Best ResponseYou've already chosen the best response.0I got the answer right
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