/saɪn; saɪn/
n (abbr 缩写 sin) (mathematics 数) (in a right-angled triangle) the ratio of the length of the side opposite one of the acute angles to the length of the hypotenuse 正弦. Cf 参看 cosine, tangent 2.

n[C]technical
[Date: 1500-1600; Language: Medieval Latin;Origin: sinus, from Latin; SINUS]
the fraction calculated for an angle by dividing the length of the side opposite it in a triangle that has a right angle, by the length of the the side opposite the right angle
→cosine, tangent