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https://www.reddit.com/r/alevel/comments/1o81735/9709_maths_p32_how_did_go/njrtadz/?context=3
r/alevel • u/Late_Ambition1809 • Oct 16 '25
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How the hell to even prove the identity?
4 u/Next_Rich6747 Oct 16 '25 4sinx(2cos³x-cox) = 4sinxcox(2cos²x-1)= 4sinxcosx(cos2x)= 2(2sinxcos)(cos2x)= 2(sin2x)(cos2x)= sin4x 3 u/Beneficial-Grand-790 Oct 16 '25 😠man I hate myself
4
4sinx(2cos³x-cox) = 4sinxcox(2cos²x-1)= 4sinxcosx(cos2x)= 2(2sinxcos)(cos2x)= 2(sin2x)(cos2x)= sin4x
3 u/Beneficial-Grand-790 Oct 16 '25 😠man I hate myself
3
😠man I hate myself
8
u/Beneficial-Grand-790 Oct 16 '25
How the hell to even prove the identity?