# NCERT Solutions for Class 10 Maths Chapter 8 - Introduction to Trigonometry

Relearn the concepts in the Maths syllabus with our NCERT Solutions for CBSE Class 10 Mathematics Chapter 8 Introduction to Trigonometry. Your trigonometry skills will be extremely useful if you aspire to have a rewarding career in the engineering stream. Practise the solutions written by our Maths experts to understand the application of the Pythagoras’ theorem to solve trigonometry problems.

To strengthen your trigonometry basics, explore TopperLearning’s CBSE Class 10 Maths concept videos and chapter notes. Our sample papers and Maths past years’ question papers are also useful for exam preparation.

## Chapter 8 - Introduction to Trigonometry Exercise Ex. 8.1

In ABC by applying Pythagoras theorem

AC^{2} = AB^{2} + BC^{2}

= (24)^{2} + (7)^{2}

= 576 + 49

= 625

AC = = 25 cm

Since A and B are acute angles, then C is a right angle.

cos A = cos B .... given

AC/AB = BC/AB

AC = BC

B =A .... angles opposite to equal sides are equal in length.

## Chapter 8 - Introduction to Trigonometry Exercise Ex. 8.2

## Chapter 8 - Introduction to Trigonometry Exercise Ex. 8.3

Given that

tan 2A = cot (A - 18)

cot (90 - 2A) = cot (A -18)

90 - 2A = A - 18

108 = 3A

A = 36

Given that

tan A = cot B

tan A = tan (90 - B)

A = 90 - B

A + B = 90

Given that

Sec 4A = cosec (A - 20)

Cosec (90 - 4A) = cosec (A - 20)

90 - 4A = A - 20

110 = 5A

A = 22

sin 67 + cos 75

= sin (90 - 23) + cos (90 - 15)

= cos 23 + sin 15

## Chapter 8 - Introduction to Trigonometry Exercise Ex. 8.4

(i) 9sec^{2}A - 9tan^{2}A

= 9(sec^{2}A - tan^{2}A)

= 9 (1) (as sec^{2}A - tan^{2}A = 1)

= 9

Hence alternative (B) is correct.

(ii) (1 + tanθ + secθ) (1 + cotθ - cosecθ)

Hence alternative (C) is correct.

(iii) (secA + tanA) (1 - sinA)

(iv)

### Other Chapters for CBSE Class 10 Mathematics

Chapter 1- Real Numbers Chapter 2- Polynomials Chapter 3- Pairs of Linear Equations in Two Variables Chapter 4- Quadratic Equations Chapter 5- Arithmetic Progressions Chapter 6- Triangles Chapter 7- Coordinate Geometry Chapter 9- Some Applications of Trigonometry Chapter 10- Circles Chapter 11- Constructions Chapter 12- Areas Related to Circles Chapter 13- Surface Areas and Volumes Chapter 14- Statistics Chapter 15- Probability### NCERT Solutions for CBSE Class 10 Subjects

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