Some Applications of Trigonometry — Question Ex 9.1 Q14
Back to all questionsA 1.2 m tall girl spots a balloon moving with the wind in a horizontal line at a height of 88.2 m from the ground. The angle of elevation of the balloon from the eyes of the girl at any instant is 60°. After sometime, the angle of elevation reduces to 30° (see figure). Find the distance travelled by the balloon during the interval.
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
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