We know from double angle formula that

Double angle formulas.jpg

 

These identities can also be used to reduce angles

Half angle formulas (Power reducing formulas) - Part 2

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Transcript

We know from double angle formula that sin 2x = 2 sin x cos x = 2 tan x / (1 + tan^2 x) cos 2x = cos^2 x - sin^2 x = 1 - 2 sin^2 x = 2 cos^2 x - 1 = 1 - tan^2 x / 1 + tan^2 x tan 2x = 2 tan x / (1 - tan^2 x) These identities can also be used to reduce angles sin x = 2 sin x/2 cos x/2 = 2 tan x/2 / (1 + tan^2 x/2) cos x = cos^2 x/2 - sin^2 x/2 = 1 - 2 sin^2 x/2 = 2 cos^2 x/2 - 1 = 1 - tan^2 x/2 / 1 + tan^2 x/2 tan x = 2 tan x/2 / (1 - tan^2 x/2)

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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.