in trigonometry, sine, cosine, and tangent represent ratios of right triangles.

Meaning, you can use them to find the ratio of an angle to certain sides.

Cosine= the ratio of the adjacent side over the hypotenuse (adj/hyp)

Sine=the opposite side to the angle over the hypotenuse (opp/hyp)

Tangent=the opposite side to the angle over the adjacent side (opp/adj)

these ratios only apply to right triangles and the sides change depending on the angle that is being used.