Question

How do you evaluate the sine, cosine, and tangent of the angle -150 degrees without using a calculator?

Answer 1

sin -150= -1/2, cos -150= -sqrt3/2, tan -150= 1/sqrt3

Explanation:

sin -150= -sin150= -sin(180-30)= -sin30= -1/2

cos -150= cos150= cos(180-30)= -cos30= -sqrt3/2

tan -150= -tan 150= -tan(180-30)= tan30= 1/sqrt3