# Proof of Cos2x Equation

Based on ABC triangle with hypotenuse 1 unit, we can prove the equation of cos2x = 2.cosx² - 1 = cosx² - sinx² = 1 – 2.sinx² as follows.

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@powBased on ABC triangle with hypotenuse 1 unit, we can prove the equation of cos2x = 2.cosx² - 1 = cosx² - sinx² = 1 – 2.sinx² as follows.

Published Date:

May 01, 2020

Updated Date:

December 12, 2023