co.sine
n.Abbr. cos(名词)缩写 cosIn a right triangle, the ratio of the length of the side adjacent to an acute angle to the length of the hypotenuse.余弦:直角三角形锐角边的边长与叙边的比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:以笛卡儿坐标系原点为圆心的单位圆的圆弦端点的横坐标,弧的长度为x ,如果 x 为正,弧的长度则从(,0)点按逆时针方向算起,若 x 为负,则按顺时针方向从(,0)点算起