CBSE 10 | Chapter 8 | Exercise 8.1 | Fully Solved CBSE | Introduction to Trigonometry | By Vivek Sir

📌 Title

CBSE Class 10 | Chapter 8 | Exercise 8.1 | Fully Solved NCERT | Introduction to Trigonometry | By Vivek Sir


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📝 Long Description

Welcome to Vivek Sir Classes 🎓, your trusted learning space for CBSE & ICSE Mathematics and Science (Classes 6–10).

In this video, we cover CBSE Class 10 Mathematics, Chapter 8 – Introduction to Trigonometry, Exercise 8.1 (NCERT) with step-by-step fully solved solutions. Every question is explained in a basic, easy-to-understand way so that students build a strong foundation in trigonometry.

👉 Exercise 8.1 Questions Covered
1️⃣ In ΔABC, right-angled at B, AB = 24 cm, BC = 7 cm. Determine:
(i) sin A, cos A
(ii) sin C, cos C

2️⃣ In Fig. 8.13, find tan P – cot R.

3️⃣ If sin A = 3/4, calculate cos A and tan A.

4️⃣ Given 15 cot A = 8, find sin A and sec A.

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

6️⃣ If ∠A and ∠B are acute angles such that cos A = cos B, then show that ∠A = ∠B.

7️⃣ If cot θ = 7/8, evaluate:
(i) (1 + sin θ)(1 – sin θ) / (1 + cos θ)(1 – cos θ)
(ii) cot² θ

8️⃣ If 3 cot A = 4, check whether

\frac{1 - \tan^2 A}{1 + \tan^2 A} = \cos^2 A - \sin^2 A

9️⃣ In ΔABC, right-angled at B, if tan A = 1/3, find the value of:
(i) sin A cos C + cos A sin C
(ii) cos A cos C – sin A sin C

🔟 In ΔPQR, right-angled at Q, PR + QR = 25 cm and PQ = 5 cm. Determine sin P, cos P and tan P.

1️⃣1️⃣ State whether the following are true or false (with justification):
(i) The value of tan A is always less than 1.
(ii) sec A = 12/5 for some value of angle A.
(iii) cos A is the abbreviation used for the cosecant of angle A.
(iv) cot A is the product of cot and A.
(v) sin θ = 4/3 for some angle θ.

✨ This session will help you:
✔️ Understand the basics of trigonometric ratios
✔️ Solve NCERT problems step-by-step
✔️ Get exam-oriented explanations
✔️ Build strong concepts for higher studies

📚 Perfect for CBSE Class 10 (2025–26 Exam Pattern) and also useful for competitive foundation.

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