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Example 15 - Chapter 3 Class 11 Trigonometric Functions
Last updated at May 29, 2018 by Teachoo
Transcript
Example 15 Prove that cos (𝜋/4 + x) + cos (𝜋/4 − 𝑥) = root(2) cos 𝑥 Solving L.H.S : cos (𝜋/4 + x) + cos (𝜋/4 − 𝑥) Using 𝑐𝑜𝑠 𝐴+𝐵+𝑐𝑜𝑠 𝐴−𝐵=2𝑐𝑜𝑠 𝐴𝑐𝑜𝑠 𝐵 cos π4+π+cos π4−x=2 cos π4 cos𝑥 = 2 × 1 2 cos𝑥 = 2 cos 𝑥 = R.H.S ∴ L.H.S = R.H.S Hence, Proved
Examples
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Example 18
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Example 20
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Example 22 Important
Example 23
Example 24 Important
Example 25 Important
Example 26 Important
Example 27 Important
Example 28 Important
Example 29 Important
Chapter 3 Class 11 Trigonometric Functions
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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.