Concise Selina Solutions for Class 9 maths Chapter 23 Trigonometrical Ratios of Standard Angles


The first trigonometric table was compiled by Hipparchus, who is consequently now known as "the father of trigonometry". Trigonometric ratios are Sine, Cosine, Tangent, Cotangent, Secant and Cosecant. The standard angles for these trigonometric ratios are 0°, 30°, 45°, 60° and 90°. Learning the values of these trigonometry angles is very necessary to solve various problems. These angles can also be represented in the form of radians such as 0, pi/6, pi/4, pi/3, and pi/2. The values of trigonometrical ratios of standard angles are fundamental to solve the trigonometrical problems. Therefore, it is necessary to remember the value of the trigonometrical ratios of these standard angles.