Trigonometry
Trigonometric identities, equations, inverse functions, and applications
Key Concepts
- Fundamental identity sin²θ + cos²θ = 1 and its variants
- Compound, multiple and half-angle formulae
- General solutions of trigonometric equations
- Inverse trigonometric functions and their domains
- Sine and cosine rules for solving triangles
Important Formulae
| Compound angle | sin(A±B) = sinA cosB ± cosA sinB |
| Double angle | cos2A = 1 − 2sin²A = 2cos²A − 1 |
| Tangent sum | tan(A+B) = (tanA + tanB)/(1 − tanA tanB) |
| Sine rule | a/sinA = b/sinB = c/sinC |
| Cosine rule | c² = a² + b² − 2ab cosC |
Quick Tips
- General solution: sinθ = sinα → θ = nπ + (−1)ⁿα.
- cosθ = cosα → θ = 2nπ ± α; tanθ = tanα → θ = nπ + α.
- Always check the domain when working with inverse trig functions.
Sample Practice Questions
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The value of cos 0° is:
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Answer: 1
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The value of sin 90° is:
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Answer: 1
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The value of sin²θ + cos²θ is:
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Answer: 1
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The value of tan 45° is:
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Answer: 1
Practice Questions
Practise randomly selected JEE questions on Trigonometry. Answers are revealed after each question.
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What are the key concepts in Trigonometry for JEE?
Fundamental identity sin²θ + cos²θ = 1 and its variants; Compound, multiple and half-angle formulae; General solutions of trigonometric equations; Inverse trigonometric functions and their domains; Sine and cosine rules for solving triangles.
Which formulae are important for Trigonometry in JEE?
Compound angle: sin(A±B) = sinA cosB ± cosA sinB; Double angle: cos2A = 1 − 2sin²A = 2cos²A − 1; Tangent sum: tan(A+B) = (tanA + tanB)/(1 − tanA tanB); Sine rule: a/sinA = b/sinB = c/sinC; Cosine rule: c² = a² + b² − 2ab cosC.
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