What is the sine cosine and tangent of 120 degrees

Use cast rule

120 degrees is in the Quadrant 2 meaning it is in the "S" quadrant AKA where Sin is positive, Cos is negative, & Tan is negative.

I found the angle of the coterminal by subtracting 120° from 180° - > 180-120=60°

Then I used the 30°-60°-90° triangle rule to find my lengths and ratios for sin, cos and tan!

The sin of 120 is the square root of 3 over 2.

The cos of 120 is - 1/2

The tan of 120 is negative square root of 3