What is 2 cos(3x) = √2. Find all Solutions.

Question

I don't even know where to start, please show work:)

Answer 1

cos(3x) = √2/2

3x = π/4 + 2kπ or 7π/4 + 2kπ, where k = 0, 1, -1, 2, -2, ...

So, x = π/12 + 2kπ/3 or 7π/12 + 2kπ/3

Answer 2

Start by dividing both sides by 3.