Sine, Tangent, and Cosine

Opposite/Hypotenuse

Sin, or sine, is short for "sine of an angle." It's a ratio that describes the relationship between the length of the side opposite an angle in a right triangle and the length of the triangle's hypotenuse (the longest side).

Cos, or cosine, is short for "cosine of an angle." It's another ratio that describes the relationship between the length of the side adjacent to an angle in a right triangle and the length of the hypotenuse.

Adjacent/hypotenuse

Opposite/adjacent

Tan, or tangent, is short for "tangent of an angle." It's a ratio that describes the relationship between the length of the side opposite an angle in a right triangle and the length of the side adjacent to that angle

In simpler terms, sin, cos, and tan can be thought of as tools to help you find missing sides or angles in a right triangle. You use sin when you know the length of the opposite side and the hypotenuse, cos when you know the length of the adjacent side and the hypotenuse, and tan when you know the length of the opposite and adjacent sides.