Question

Solve,
(pic attached)

Answer 1

first algebra to get
\[\cos(x)=-\frac{\sqrt{2}}{2}\]

Answer 2

i.e. subtract cosine from both sides, then divide by 2

Answer 3

then see if you know a number (angle) whose cosine is \(-\frac{\sqrt{2}}{2}\)
answer will depend on whether you are working in degrees or radians, and also on what interval you need your answer, since there are an infinite number of solutions

Answer 4

2pi/3, 4pi/3?

Answer 5

@satellite73

Answer 6

no

Answer 7

\(\frac{3\pi}{4}, \frac{5\pi}{4}\)

Answer 8

i think you were thinking of \(-\frac{\sqrt{3}}{2}\) instead of \(-\frac{\sqrt{2}}{2}\)

Answer 9

yeah, thanks :D