Uploaded October 2022 | Updated September 2026, 1 week ago

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In this video, I derived formulas for finding the sin and cos of the double of an angle. In my derivation, I used some formulas that I already derived in previous videos. You can access those below:

PROOF of sin(a+b): youtu.be/xtAjcfztc-4

PROOF of cos(a+b): youtu.be/UtNyHeWBqCk

PROOF that sin^2(a)+cos^2(a)=1: youtu.be/FLuG9MnrKjE

#trigonometry #maths #math #science #geometry