Question

Evaluate w/o using a calulator!
sin(-150)
Please explain how to solve these types or show work! Thank you!

Answer 1

sin(-90 - 60) = - cos(60)

Answer 2

that is one way
another is to find the reference angle:
-150 puts you in 3rd quadrant...sin x is neg
180 -150 = 30, you are 30 degrees away from axis

--> -sin(30) = -1/2

Answer 3

90 rotation ratio change sin=>cos; cos =>sin
180 rotation ratio does't change. sin=>sin; cos => cos

use CAST to find out if they are positive or negative,

Answer 4

i'm trying to figure out tan 240 now... Thanks for helping!