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 Question from MaryBeth, a student: find all solutions of the following equation in the interval [0,pi] 2cos^x+cosx=sin^2x

I presume that you mean cos^2 (x) rather than cos^x?

To solve this, or problems like it, rewrite $\sin^2(x)$ as $1 - \cos^2(x).$
Then let $u = \cos(x)$ and solve the polynomial equation by whatever method works in this case.

Good Hunting!
RD

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