Trig calculations are mathematical equations used to measure angles, lengths, and distances in a triangle. Slopes, cosines, and RADII are all terms used in trig calculations. Slopes refer to the steepness of a line, cosines refer to the ratio of the length of the side adjacent to an angle to the length of the hypotenuse, and RADII refer to the length of a line segment from the center of a circle to its circumference.