# Trigonometrical Ratios Class-9 RS Aggarwal ICSE Maths Goyal Brothers

Trigonometrical Ratios Class-9 RS Aggarwal ICSE Maths Goyal Brothers Prakashan Chapter-20. We provide step by step Solutions of Exercise / lesson-20 Trigonometrical Ratios for ICSE Class-9 RS Aggarwal Mathematics .

Our Solutions contain all type Questions with Exe-20 (A), Exe-20 (B), , Exe-20 (C), and  Exe-20 (D), and Notes to develop skill and confidence. Visit official Website for detail information about ICSE Board Class-9 Mathematics.

## Trigonometrical Ratios Class-9 RS Aggarwal ICSE Maths Goyal Brothers Prakashan Chapter-20

–: Select Topics :–

Notes on Trigonometrical Ratios

Exe-20 (A),

Exe-20 (B),

Exe-20 (C),

Exe-20 (D),

### Notes on Trigonometrical Ratios

The ratio between the lengths of a pair of two sides of a right-angled triangle is called a Trigonometrical Ratio. The three sides of a right-angled triangle give six trigonometrical ratios; namely sine, cosine, tangent, cotangent, secant, and cosecant.

#### Definition

Trigonometry is the study of relationships between the sides and angles of a triangle

The word “trigonometry” is derived from the Greek words “tri” (meaning three), “gon”(meaning sides) and “metron”(meaning measure)

#### Right angled triangle ABC

• Side AC is called the hypotenuse of the right angle
• Side AB is called the side adjacent to angle A or base
• Side BC is called the side opposite to angle A or perpendicular
• If we consider angle C, then
• Side BC is called the side adjacent to angle C
• Side AB is called the side opposite to angle C

#### Important properties

• Each trigonometric ratio is a real number and has no unit
• The values of the trigonometric ratios of an angle do not vary with the lengths of the sides of the triangle, if the angle remains the same
• Since the hypotenuse is the longest side in a right triangle, the value of sin A or cos A is always less than 1 (or, in particular, equal to 1)

### Trigonometrical Ratios Class-9 RS Aggarwal ICSE Maths Goyal Brothers Prakashan  Exe-20 (D),

–: End of Trigonometrical Ratios Class-9 RS Aggarwal ICSE Class-9th Maths Solutions   :–

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