Will you pretty please help me because I don't understand?

Tangents, sines, and cosines are trigonometric functions. A tangent is equal to the ratio of the sides (other than the hypotenuse) opposite and adjacent to an angle in a right triangle. A sine is equal to the ratio of the side opposite a given angle (in a right triangle) to the hypotenuse. A cosine is equal to the ratio of the side adjacent to an acute angle (in a right-angled triangle) to the hypotenuse. Also learn the Law of Sines, the Law of Cosines, and maybe some trigonometric identities.