Trigonometric Ratios


trigonometry is concerned with the measurement and calculation of the lengths of sides and the sizes of angles of triangles.

there are three basic ratios called the sine, the cosine and the tangent of the angle. these are abbreviated to sin, cos and tan.

greek letters are often used to stand for angles in triangles.

Key Skills

find the trigonometric ratios for any angle using calculator.

know the formulae of the three trigonometric ratios of sine, cosine and tangent.


trigonometrytrigonometric ratiossinecosinetangent, right angleopposite sideadjacent sidehypotenuse.