In ABC species of right triangle, A and B represent right angles and C represents hypotenuse. Take angle a as an example.

So there are:

SinA: stands for sine. The ratio of the opposite side of angle α to the hypotenuse,

Sina = account

CosA: for cosine. The ratio of adjacent straight edges to the hypotenuse of angle α,

cosA=b/c

Tana: It means tangent. The ratio of the opposite side of angle A to the adjacent straight side, tana = a/b.

CtanA: indicates cotangent. The ratio of adjacent straight edges to opposite edges of Angle A, tana = b/a.

ArctanA: It means arc tangent.