Sine

How it is used

One of the three basic trigonometric ratios, remembered with SOH CAH TOA (sine = opposite over hypotenuse). It is also a function: the sine curve repeats every 360°, or 2π radians. 'sin x' is read 'sine x'.

Example sentences

1. Use the sine of 40° to find how high the ladder reaches.

2. The sine rule works for any triangle, not only right triangles.

Common collocations

• sine of an angle
• sine rule
• sine curve
• inverse sine

Related terms

• cosineIn a right triangle, the ratio of the side next to an angle (the adjacent side) to the hypotenuse; it is written cos, so cos 60° = 0.5.
• tangentIn a right triangle, the ratio of the opposite side to the adjacent side, written tan; also a straight line that touches a curve at a point without cutting across it there.
• hypotenuseThe longest side of a right triangle, which is the side opposite the right angle.
• radianA unit for measuring angles: the angle at the centre of a circle made by an arc as long as the radius. A full turn is 2π radians, or 360°.
• right angleAn angle of exactly 90 degrees, like the corner of a square, usually marked on diagrams with a small square.