Question

cos x + sqrt2= -cos x for x over the interval [0,2pi]
I have no idea how to approach this.

Answer 1

@Mertsj @satellite73 mind seeing if you could help me?

Answer 2

I know I'm solving for x, but that is all.

Answer 3

1) add \(\cos(x)\) to both sides
2) subtract \(\sqrt2\) from both sides
3) divide both sides by \(2\)

you end up with
\[\cos(x)=-\frac{\sqrt2}{2}\]

Answer 4

that number should look real familiar, find \(x\) so that \(\cos(x)=-\frac{\sqrt2}{2}\)