What is the easiest way to find the maximum of $9\cos(t) - 8\cos (3t)$?
What is the easiest way to find the maximum of $9\cos(t) - 8\cos(3t)$?
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calculus
trigonometry
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0The standard first derivative test worked for me. You may want to look up the triple angle formulas if you get stuck. If you know some complex variables, you can derive these fairly easily with DeMoivre's formula and Euler's formula – 2010-10-28
1 Answers
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Express $\cos(3t)$ in terms of $\cos(t)$ and differentiate with respect to $t$ or $\cos(t)$.