名詞 cosine:

1. ratio of the adjacent side to the hypotenuse of a right-angled triangle
   同義詞：cos

co.sine

n.Abbr. cos（名詞）縮寫 cos
In a right triangle, the ratio of the length of the side adjacent to an acute angle to the length of the hypotenuse.
余弦：直角三角形銳角邊的邊長(zhǎng)與敘邊的比
The abscissa at the endpoint of an arc of a unit circle centered at the origin of a Cartesian coordinate system, the arc being of lengthx and measured counterclockwise from the point (, 0) if x is positive or clockwise if x is negative.
余弦：以笛卡兒坐標(biāo)系原點(diǎn)為圓心的單位圓的圓弦端點(diǎn)的橫坐標(biāo)，弧的長(zhǎng)度為x ，如果 x 為正，弧的長(zhǎng)度則從（，0）點(diǎn)按逆時(shí)針方向算起，若 x 為負(fù)，則按順時(shí)針方向從（，0）點(diǎn)算起