RD Sharma Solutions for Class 11 Maths Chapter 8 is an important scoring chapter. By understanding the formulas and their correct applications, students can easily secure 8–12 marks in exams. The Transformation Formulae in RD Sharma Class 11 Maths are designed by subject experts, following the latest CBSE syllabus. These solutions are available in a free PDF format on HT. In Chapter 8, students will learn about the derivation and application of transformation formulas within two sets of trigonometric identities.
RD Sharma Solutions Class 11 Maths -Transformation Formulae Question with Answers
- Express sin A + sin B in product form.
sin A + sin B = 2 sin[(A + B)/2] cos[(A - B)/2]
- Express sin A - sin B in product form.
sin A - sin B = 2 cos[(A + B)/2] sin[(A - B)/2]
- Express cos A + cos B in product form.
cos A + cos B = 2 cos[(A + B)/2] cos[(A - B)/2]
- Express cos A - cos B in product form.
cos A - cos B = -2 sin[(A + B)/2] sin[(A - B)/2]
- Express sin x cos y in sum form.
sin x cos y = 1/2 [sin(x + y) + sin(x - y)]
- Express cos x sin y in sum form.
cos x sin y = 1/2 [sin(x + y) - sin(x - y)]
- Express cos x cos y in sum form.
cos x cos y = 1/2 [cos(x + y) + cos(x - y)]
- Express sin x sin y in sum form.
sin x sin y = 1/2 [cos(x - y) - cos(x + y)]
- Simplify: sin 75° + sin 15°
= 2 sin 45° cos 30° = √3/√2
- Simplify: cos 70° + cos 10°
= 2 cos 40° cos 30°
- Simplify sin 50° − sin 10°
= 2 cos 30° sin 20°
- Simplify cos 100° − cos 40°
= -2 sin 70° sin 30°
- Express sin 5x + sin 3x in product form.
= 2 sin 4x cos x
- Express cos 7x − cos 3x in product form.
= -2 sin 5x sin 2x
- Simplify sin 3x cos 2x.
= 1/2 [sin 5x + sin x]
- Simplify cos 4x sin 3x.
= 1/2 [sin 7x - sin x]
- Simplify sin 7x sin 5x.
= 1/2 [cos 2x - cos 12x]
- Simplify cos 6x cos 2x.
= 1/2 [cos 8x + cos 4x]
- Express sin 120° + sin 60° as product.
= √3
- Simplify cos 150° + cos 30°
= 0
- Find sin 36° + sin 14°
= 2 sin 25° cos 11°
- Find cos 70° − cos 50°
= -2 sin 60° sin 10°
- Simplify sin 9x + sin 3x
= 2 sin 6x cos 3x
- Express sin 8x cos 3x in sum form
= 1/2 [sin 11x + sin 5x]
- Express cos 5x sin 2x in sum form
= 1/2 [sin 7x - sin 3x]
Benefits of Solving RD Sharma Solutions Class 11 Maths - Transformation Formulae
1. Mastery Over Trigonometric Transformations
Solving RD Sharma’s Transformation Formulae exercises ensures students gain complete clarity on sum-to-product and product-to-sum identities. These are foundational formulas frequently used in advanced trigonometry, calculus, and competitive exams like JEE, NEET, CUET, etc.
2. Step-by-Step Concept Clarity
RD Sharma provides detailed step-by-step solutions, helping students understand the logic and derivation behind every formula. This improves analytical thinking and reduces the chances of rote learning.
3. Better Speed and Accuracy in Exams
By repeatedly practicing transformation formula questions, students learn to quickly identify patterns in trigonometric expressions. This directly boosts speed and accuracy, which is crucial for time-bound exams.
4. Foundation for Complex Topics
Transformation Formulae are building blocks for more complex topics in Class 11 and 12 Maths like:
-
Trigonometric Equations
-
Integration & Differentiation of Trigonometric Functions
-
Inverse Trigonometry
By mastering these early, students can handle tougher chapters effortlessly later on.
5. High Scoring Topic in Board Exams
Transformation Formulae typically feature in short answer and long answer questions in Class 11 exams. Practicing RD Sharma improves students' ability to write perfect board-level answers with correct formula applications.
6. Essential for Competitive Exams
For JEE, NDA, NEET, and other entrance tests, transformation identities simplify complex problems quickly. RD Sharma’s exercises align well with these exam patterns, offering ample variety and difficulty levels.
7. Development of Problem-Solving Skills
Through varied question types (MCQs, simplifications, proofs), students develop a problem-solving mindset, learning when and how to apply specific formulas strategically.
8. Boosts Mathematical Confidence
Regular practice helps students overcome fear of trigonometry and builds confidence, ensuring they feel prepared and motivated throughout their academic journey.
Frequently Asked Questions
Chapter 8 of RD Sharma Class 11 Maths covers sum-to-product, product-to-sum, and sum-difference trigonometric identities. Key topics include:
- Formulae for sin A + sin B, sin A − sin B
- Formulae for cos A + cos B, cos A − cos B
- Product to sum identities like sin x sin y, cos x cos y, sin x cos y
Applications in simplifying trigonometric expressions.
These formulas help in simplification, derivation, and proof-type questions in board and competitive exams.
Practicing RD Sharma Chapter 8 helps you:
- Master essential trigonometric transformations
- Improve speed and accuracy in problem-solving
- Build a strong base for higher-level maths like calculus
- Score better in school exams, JEE, and other entrance exams
With step-wise explanations, RD Sharma ensures students understand the concept behind every formula, making learning easier and more effective.
Yes, RD Sharma is a great foundation for JEE preparation, especially for building core concepts of trigonometry. The Transformation Formulae chapter covers important identities, helps in quick simplifications, and improves logical reasoning. For JEE Advanced, you may later practice additional problem sets, but RD Sharma is ideal for strengthening fundamentals.
Absolutely! The product-to-sum and sum-to-product identities are frequently asked in CBSE Class 11 exams, often appearing in both short answer and long answer sections. Questions like expression simplification and proving identities are based directly on these formulas, making this chapter highly scoring.
You can access RD Sharma Class 11 Chapter 8 Solutions PDF from trusted educational platforms like Infinity Learn, which provides step-by-step solved answers for all exercises. These solutions help in self-study, doubt clearance, and revision for exams. Always prefer updated, syllabus-aligned solutions for the best preparation.