Trignometry- Sine, COS, Tangent

In a right-angled triangle, the size of any angle is related to the ratio of the lengths of any two sides by the trigonometric functions. The basic functions are sine, cosine, and tangent.
These functions are based on the similarity of triangles that have a right angle and one other angle in common. Imagine an angle A formed by the intersection of lines AB and AC (see above). A third line drawn perpendicularly up from AC gives a right-angled triangle. The sides of such a triangle will always be in the same ratio to one another, no matter where the third line intersects AC.

Sine
The sine of angle A is the ratio of the lengths BC to AB.

Cosine
The cosine of angle A is the ratio of the lengths AC to AB.

Tangent
The tangent of angle A is the ratio of the lengths BC to AC.