Question

evaluate cos210

Answer 1

Do you have a unit circle?

Answer 2

yes

Answer 3

Ok, so 210 is 30degrees more than 180. So, you can use the unit circle to find the coordinates of 210. x is cos, so it's going to be the x of the (x,y) coordinate of 210degrees. It will be a negative number.

Answer 4

i know that part but isnt it cos cos - sin sin formula

Answer 5

if it was, say, 195, then you'd have to use the cos cos- sin sin

Answer 6

so is the answer - radical 3 over 2

Answer 7

Yep.