As shown in the right figure, when the connecting lines AB, AC and BC of three points A, B and C on the plane form a right triangle, where ∠ACB is a right angle. For the angle between AB and AC ∠BAC:

Opposite) a=BC

Hypotenuse) h=AB

Adjacent) b=AC

fundamental function

English

abbreviate

express

language description

sine function

sine

sin a/h

The opposite side of ∠A is larger than the hypotenuse.

cosine function

cosine

cos b/h

The adjacent side of ∠A is greater than the hypotenuse.

Tangent function

tangent

Tan a/b

The opposite side of ∠A is better than the adjacent side.