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Example 8 - Chapter 8 Class 10 Introduction to Trignometry
Last updated at August 11, 2026 by Teachoo
Trignometric ratios of Specific Angles - Evaluating
Chapter 8 Class 10 Introduction to Trignometry
Concept wise
- Finding sin cos tan
- Finding sin cos when sides of a triangle are given
- Finding ratios when other ratios are given
- Finding values of expressions
- Proving
-
Trignometric ratios of Specific Angles - Evaluating
- Trignometric ratios of complementry angles
- Expressing ratios in other ratios
- Evaluating using Trignometric Identities
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Transcript
Example 8 If sin (A – B) = 1/2 , cos (A + B) = 1/2 , 0° ∠ A + ∠ B ≤ 90° , A > B, find A and B. Given data, sin (A – B) = 𝟏/𝟐 But we know that sin 30° = 1/2 Thus, sin (A – B) = sin 30° A – B = 30° cos (A + B) = 𝟏/𝟐 But we know that cos 60° = 1/2 Thus cos (A + B) = cos 60° A + B = 60° Our equations are A − B = 30° …(1) A + B = 60° …(2) Adding (1) and (2) A – B + A + B = 60° + 30° 2A = 90° A = (90°)/2 A = 45° Putting A = "45°" in (2) A + B = 60° 45° + B = 60° B = 60° − 45° B = 15° Hence, A = 45° , B = 15°
