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I'm studying for an exam and am stuck on a trigonometry question. Could anybody help me out?

The question is:

Solve the equation cos3x = 1/2, for x is an element of R, (where x is in radians)

The answer is:

x = pi/9 + 2npi/3

or

x = 5pi/9 + 2npi/3

where n is an element of Z

Sincere thanks

John

My attempt

Well we know that cos (pi/3) = 1/2

But cos 3x = 1/2 and are trying to figure out what x is.

So what times 3 will give you pi/3. That would be pi/6.

3 * (pi/6) = pi/3

cos (3*(pi/6)) = 1/2

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# Homework Help: Trigonometry question

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