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Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class


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Ex 3.3, 14 Prove that sin 2x + 2sin 4x + sin 6x = 4cos2 x sin 4x Solving L.H.S. sin 2x + 2sin 4x + sin 6x = (sin 6x + sin 2x) + 2sin 4x = 2 sin ((6𝑥 + 2𝑥)/2) cos ((6𝑥 − 2𝑥)/2) + 2sin 4x = 2 sin (8𝑥/2) cos (4𝑥/2) + 2sin 4x = 2 sin 4x cos 2x + 2sin 4x = 2 sin 4x (cos 2x + 1) = 2 sin 4x ( 2cos2x – 1 + 1) = 2 sin 4x (2cos2x) = 4 sin 4x cos2x = R.H.S Hence L.H.S = R.H.S Hence proved

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.