Толковый словарь английского языка - sine

noun Etymology: Medieval Latin sinus, from Latin, curve Date: 1593 the trigonometric function that for an acute angle is the ratio between the leg opposite the angle when it is considered part of a right triangle and the hypotenuse, a trigonometric function sin θ that for all real numbers θ is exactly equal to the ~ of an angle of measure θ in radians and that is given by the sum of the alternating series sin θ = θ θ3/3! + θ5/5! θ7/7! + θ9/9! . . .