Cos x + cos y formula
Ex 3.3, 11 Important
Misc 3
Misc 4 Important
Ex 3.3, 14 You are here
Ex 3.3, 15
Misc 5
Misc 7 Important
Example 16 Important
Ex 3.3, 16 Important
Ex 3.3, 17
Ex 3.3, 18 Important
Ex 3.3, 19
Ex 3.3, 20
Ex 3.3, 21 Important
Example 17 Important
Misc 6 Important
cos x + cos y formula
Last updated at April 16, 2024 by Teachoo
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