OP Malhotra Notes on Trigonometrical Ratios Class-9 S.Chand ICSE Maths 2026-27. We Provide Step by Step Notes on Trigonometry Ratios, Finding Angles and Trigonometrical Applications with Chapter Test of S Chand OP Malhotra Maths . Visit official Website CISCE for detail information about ICSE Board Class-9.
OP Malhotra Notes on Trigonometrical Ratios Class-9 S.Chand ICSE Maths 2026-27
Trigonometric Ratios Definition :
It is defined as the values of all the trigonometric function based on the value of the ratio of sides in a right-angled triangle. The ratios of sides of a right-angled triangle with respect to any of its acute angles are known as the trigonometric ratios of that particular angle. Consider a right-angled triangle, right-angled
- sine: Sine of an angle is defined as the ratio of the side opposite(perpendicular side) to that angle to the hypotenuse.
- cosine: Cosine of an angle is defined as the ratio of the side adjacent to that angle to the hypotenuse.
- tangent: Tangent of an angle is defined as the ratio of the side opposite to that angle to the side adjacent to that angle.
- cosecant: Cosecant is a multiplicative inverse of sine.
- secant: Secant is a multiplicative inverse of cosine.
- cotangent: Cotangent is the multiplicative inverse of the tangent.
Practice Questions on Finding Trigonometrical ratios :- Exercise-19(a)
Finding Angles
sin θ = Perpendicular / Hypotenuse
cos θ = Base / Hypotenuse
tan θ = Perpendicular / Base
cot θ = Base / Perpendicular
sec θ = Hypotenuse / Base
cosec θ = Hypotenuse / Perpendicular
Practice Questions on Finding Angles :- Exercise-19(b)
Trigonometry Applications :
Trigonometry is one of the most important branches of mathematics. Some of the applications of trigonometry are:
- Measuring the heights of towers or big mountains
- Determining the distance of the shore from the sea
- Finding the distance between two celestial bodies
- Determining the power output of solar cell panels at different inclinations
- Representing different physical quantities such as mechanical waves, electromagnetic waves, etc.
It is evident from the above examples that trigonometry has its involvement in a major part of our day-to-day life and much more. In most of the applications listed above, something was being measured and that is what trigonometry is all about.
Practice Questions on Trigonometry Application :- Exercise-19(c)
and for problems on this topic is :- Exercise-19(d)
In this chapter, we study all the topics on Trigonometrical Ratios like Trigonometry Ratios, Finding Angles and Trigonometrical Applications and do some practice questions also. Here we solve extra practice questions on this chapter for better understanding.
For extra practice questions on Trigonometrical Ratios :- Chapter Test
— : End of Trigonometry Ratios OP Malhotra S Chand Solutions :–
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