Sine; In a right triangle, the ratio of the opposite side to the hypotenuse of any acute angle ∠A is called the sine of angle A;

Cosine: in a right triangle, the ratio of the adjacent side to the hypotenuse of any acute angle ∠A is called the cosine of angle A;

Tangent: in a right triangle, the ratio of the opposite side to the adjacent side of any acute angle ∠A is called the tangent of angle A;

Cotangent: in a right triangle, the ratio of the adjacent side to the opposite side of any acute angle ∠A is called the cotangent of angle A.

Relationship:

In a right triangle, the sine value of any acute angle is equal to the cosine value of another acute angle;

The product of sine and cosine at any angle is 1.