Question

find the general solution of equation cos3x=-1/2​

Answer 1

Step-by-step explanation:

cos3x=-1/2

cos3x=-cos60°

3x=-60°

x=-20°

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Answer 2

Answer:

$\cos(3x) = - \frac{1}{2} \\ \cos(3x) = \cos( \frac{2\pi}{3} ) \\ 3x = 2n\pi \frac{ + }{} \frac{\pi}{3} \\ x = \frac{2n\pi}{3} \frac{ + }{} \frac{\pi}{9}$