I am trying to find absolute maximum and

Rex Maxwell

Rex Maxwell

Answered question

2022-04-01

I am trying to find absolute maximum and absolute minimum values for f(x)=cos(x)+sin(2x) on the interval [0,π2]
I started off by finding the derivative:
f(x)=sinx+2cos(2x)
Then I tried to find the critical numbers. But that's where I ran amuck. I came up with:
sinx=2cos(2x)
How do I go about solving for x?

Answer & Explanation

Melody Gamble

Melody Gamble

Beginner2022-04-02Added 10 answers

use that
cos(2x)=12sin2(x)
plugging this in your equation we get
sin(x)+2(12sin2(x))=0
this is a quadratic equation in sin(x)

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