To use trigonometric functions to find sides and angles of right triangles. the functions sine, cosine, and tangent are called trigonometric functions (often shortened to "trig functions"). trigonometric just means "measuring triangles." these functions are called trigonometric because they are used to find the lengths of sides or the measures of angles for right triangles. they can be used, with some effort, to find measures of any triangle, but in this problem we will focus on right triangles. right triangles are by far the most commonly used triangles in physics, and they are particularly easy to measure.