how to find the sin cos and tan of 300 degrees?

Place it on a graph in quadrant IV.

The reference angle (the angle formed with the x-axis) is 60°.

The side opposite the 60° angle has value -√(3)/2.

The side adjacent the 60° angle has value 1/2.

The hypotenuse has value 1.

sin(300°)  =  opposite side / hypotenuse  =  (-√(3)/2) / 1  =  -√(3)/2.

cos(300°)  =  adjacent side / hypotenuse  =  (1/2) / 1  =  1/2.

tan(300°)  =  opposite side / adjacent side  =  (-√(3)/2) / (1/2)  =  -√(3)/2.