NCERT Class 10 Maths Chapter 8 Trigonometry Free video classes and solutions

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Welcome to the free live video classes of the chapter 8 Introduction to Trigonometry. The classes are taken by our maths expert Smt Radhika Polina and you will get thorough in all the basic concepts in this introductory class.

NCERT Class 10 Maths Video Lessons and exercise solutions

Introduction to Trigonometry| Part-1|Explanation of Basic Concepts

In this video teacher explains the concepts of Trigonometric Ratios in detail


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NCERT Class 10 Maths Video Lessons and exercise solutions

Introduction to Trigonometry| Part-2|Explanation of Basic Concepts 2

In this class teacher explains the rest of the topic- trigonometric ratios, trigonometric ratio table, trigonometric identities etc..

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NCERT Class 10 Maths Video Lessons and exercise solutions

Introduction to Trigonometry| Part-3|Exercise[b] 8.1 Problems (1 to 5) solutions [/b]

1. In  ΔABC, right-angled at B, AB=24cm,, BC=7cmcm, determine:
(i) sinA,cosA
(ii) sin C,

2.  In the given figure, find tanP −cot R.

3. If sin A=3/4 calculate cosA and tanA.

4. Given 15cotA=8, find sinA and secA.

5. Given secθ=13/12, calculate all other trigonometric ratios.

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NCERT Class 10 Maths Video Lessons and exercise solutions

Introduction to Trigonometry| Part-4| Exercise 8.1 Problems (6-11)


The following problems are taken in this class
 
6. If ∠A and ∠B are acute angles such that cosA=cosB, then show that ∠A=∠B

7. If cotθ= 7/8 evaluate:
(i) (1+sinθ)(1−sinθ) / (1+cosθ)(1−cosθ)
(ii) cot2θ

8. If 3cotA=4, check whether 

1−tan2A /1+tan2A =cos2A−sin2A or not.

9. In the ΔABC right-angled at B, if tanA= 1 /√3  find the value of:

(i) sin A cos C+ cos Asin C

(ii) cos A cos C− sin A sin C

10. In ΔPQR, right-angled at Q, PR+QR=25cm and PQ=5cm. Determine the values of sinP,cosP and tanP.

11. State whether the following are true or false. Justify your answer.
(i) The value of tanAs always less than 1.
(ii) secA= 12/ 5 for some value of ∠A.
(iii) cosA is the abbreviation used for the cosecant of ∠A
(iv) cotA is the product of cot and A
(v) sinθ= 4/3 , for some ∠θ

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NCERT Class 10 Maths Video Lessons and exercise solutions

Introduction to Trigonometry| Part-5| Exercise 8.2 problems 1 main(i,ii,iii)



Teacher explains the following problems in this video

(i) sin60∘cos30∘+sin30∘cos60∘
(ii) 2tan245∘+cos230∘−sin260∘
(iii) cos45∘/ sec30∘+cosec30∘

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NCERT Class 10 Maths Video Lessons and exercise solutions

Introduction to Trigonometry| Part-6|Problems 1 main(iv,v),2,3&4

Teacher explains the solutions to the following problems


(iv) 

sin30∘+tan45∘−cosec60∘ /sec30∘+cos60∘−cot45∘

(v) 

5cos260∘+4sec230∘−tan245∘/sec230∘+cos230∘

Choose the correct option and justify your choice:
(i) 

2tan30∘/1+tan230∘

 (A) sin60∘
(B) cos60∘
©Â tan60∘
(D) sin60∘

(ii) 

1−tan245∘ / 1+tan245∘

(A) tan90∘
(B) 1
©Â sin45∘
(D) 0∘

(iii) sin2A=2sinA is true when A=
(A) 0∘
(B) 30∘
©Â 45∘
(D) 60∘

(iv) 

2tan30∘ /1−tan230∘

(A) cos60∘
(B) sin60∘
©Â tan60∘
(D)  sin30∘



3. If tan(A + B)=√3t and tan(A−B)= 1/√3
;0∘<(A + B)≤90∘,A>B,
find A B.

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NCERT Class 10 Maths Video Lessons and exercise solutions

Introduction to Trigonometry| Part-7| Exercise 8.3

Teacher explains the following question in this class


8.3.1 Evaluate:
(i)  

sin180/ cos720

(ii) 

tan260/ cot640

(iii) cos480−sin420

(iv) cosec310−sec590

8.3.2 
Show that:
(i) tan48∘tan23∘tan42∘ tan67∘=1

(ii) cos38∘cos52∘−sin38∘ sin52∘=0

8.3.3 If tan2A=cot(A−18∘), where 2A an acute angle, find the value of A.

8.3.4 If tanA=cotB, prove that A+B=90∘.

8.3.5  If sec4A=cosec(A−20∘),,where 4A is an acute angle, find the value of A.

8.3.6 If A, B and C are interior angles of a triangle ABC, then show that
sin(B+C/2 )=cos A/ 2

8.3.7 Express sin67∘+cos75∘ in terms of trigonometric ratios of angles between 0∘ and 45∘ .


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NCERT Class 10 Maths Video Lessons and exercise solutions

Introduction to Trigonometry| Part-8| Exercise 8.4 Problems ((1,2,3 & 4)


8.4.1 Express the trigonometric ratios sinA, secA and  tanA in terms of cotA.


8.4.2 Write all the other trigonometric ratios of∠A in terms of secA

8.4.3 Evaluate

(i)  sin263∘+sin227∘ /cos217∘+cos273∘

(ii) sin25∘cos65∘+cos25∘ sin65∘

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NCERT Class 10 Maths Video Lessons and exercise solutions

Introduction to Trigonometry| Part-8| Exercise 8.4 Problems 5th main(I to III)


Teacher solves the following  problems in this class




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NCERT Class 10 Maths Video Lessons and exercise solutions

Introduction to Trigonometry| Part-9| Exercise 8.4 Problems 5th main(IV to VI)

Teacher introduces the following problems and finds the solutions

Prove the following identities, where the angles involved are acute angles for which the expressions are defined.





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NCERT Class 10 Maths Video Lessons and exercise solutions

Introduction to Trigonometry| Part-10| Exercise 8.4 Problems 5th main(VII to x)

In this class the following problems are solved

Prove the following identities, where the angles involved are acute angles for which the expressions are defined


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