ML Aggarwal Solutions for Class 9 Maths Chapter 17 Trigonometric Ratios

Trigonometry is the branch of mathematics that deals with the study of relationships between sides and angles of a triangle. It is derived from Greek words, Tri meaning Three; Gon means Angle and Metron means Measure.

The ratios of the sides of a right triangle are called trigonometric ratios. Three common trigonometric ratios are the sine (sin), cosine (cos), and tangent (tan). They are widely used in all sciences that are related to geometry, such as navigation, solid mechanics, celestial mechanics, geodesy, and many others.


The trigonometric ratios are special measurements of a right triangle (a triangle with one angle measuring 90°). There are three basic trigonometric ratios: sine, cosine, and tangent. Given a right triangle, you can find the sine (or cosine, or tangent) of either of the non- 90° angles. In trigonometry, trigonometric ratios are derived from the sides of a right-angled triangle. There are six 6 ratios, such as sine, cosine, tangent, cotangent, cosecant, and secant.