Introduction to Trigonometry — Question Ex 8.2 Q4
Back to all questionsState whether the following statements are true or false. Justify your answer.
(i) sin (A + B) = sin A + sin B.
(ii) The value of sin θ increases as θ increases.
(iii) The value of cos θ increases as θ increases.
(iv) sin θ = cos θ for all values of θ.
(v) cot A is not defined for A = 0°.
CBSE Class 10 Introduction to Trigonometry — Complete Guide
Trigonometry is a high-weightage topic with Ch 8 + Ch 9 together carrying 12 marks. Identity proofs and complementary angle problems are board favourites.
Quick Revision: Key Concepts
- Ratios: sin = O/H, cos = A/H, tan = O/A (SOH-CAH-TOA)
- Standard values: sin 30° = 1/2, sin 45° = 1/√2, sin 60° = √3/2
- Complementary: sin(90°−A) = cos A, tan(90°−A) = cot A
- Identities: sin²A + cos²A = 1, 1 + tan²A = sec²A, 1 + cot²A = cosec²A
Most Important Questions
- Evaluate expressions using standard angle values
- Prove trigonometric identities (LHS = RHS)
- Find other ratios given one ratio
- Complementary angle simplification problems
About Bright Tutorials
Bright Tutorials, Hariom Nagar, Nashik Road, provides expert coaching for CBSE and ICSE students. Our experienced faculty ensures comprehensive preparation for board exams with personalised attention and 3-tier differentiation for students of all levels. Contact us at 9403781999 or visit brighttutorials.in.