How do I figure out sin x and cos x given x?

Question

I have to use the table given in the book in order to know.
For example,
x = 2pi/3, so sin x = .87 and cos x = -.50
How do you figure out sin x and cos x from just x = 2pi/3
I tried using my calculator but the answer is different.

Answer 1

It's because you're working in degrees. Change it to radians, and you'll be fine.

Answer 2

Does your calculator have a radians setting? If not, you may be trying to figure out the sin of 2.094 instead of the sin of 120, which is 2pi/3 in degrees.

Answer 3

If you use the inverse function of Sin (SIN -1) which is the second function of sin on your calculator, when it comes to cos you go with the sign, 120 deg is in the second quadrant thus the value would have a negative sign and 60 & 120 deg are complementary angle if you draw them in the sys of axes you will see that they are symetric.remember that all trig function are + in the 1st quad, sin is + in the 2nd, tan inthe 3rd and and ccos is + in the 4th. I HOPE GAVE YOU ALL THE 411