The ratios of the sides of a right triangle are called trigonometric ratios. Three common
trigonometric ratios are the sine (sin), cosine (cos), and tangent (tan). These are defined for
acute angle below:
Triangle A B C with angle A C B being ninety degrees. Angle B A C is the angle of reference.
Side B C is labeled opposite. Side A C is labeled adjacent. Side A B is labeled hypotenuse.
In these definitions, the terms opposite, adjacent, and hypotenuse refer to the lengths of the sides.
SOH-CAH-TOA: an easy way to remember trig ratios
The word SOH-CAH-TOA helps us remember the definitions of sine, cosine, and tangent.
Here's how it works: