Question

Please help!
In the interval [0,pi) what are the angles for cos x = square root 2 / 2 ?

Answer 1

only one in that interval is 45 degrees, or if you are working in radian \(\frac{\pi}{4}\)

Answer 2

look at unit circle on the last page of the attached cheat sheet
cosine is the first coordinate. you will see that where the first coordinate \(\frac{\sqrt{2}}{2}\) the angle is \(\frac{\pi}{4}\)

Answer 3

Wow thank you so much! That cheat sheet helps a lot!