Prove the trigonometric identity: \(\displaystyle{\frac{{{\left({{\cos}^{{3}}{x}}-{{\sin}^{{3}}{x}}\right)}}}{{{\left({\cos{{x}}}-{\sin{{x}}}\right)}}}}={\frac{{{\left({2}+{\sin{{2}}}{x}\right)}}}{{{2}}}}\)

Nathanael Hansen

Nathanael Hansen

Answered question

2022-03-31

Prove the trigonometric identity:
(cos3xsin3x)(cosxsinx)=(2+sin2x)2

Answer & Explanation

pastuh7vka

pastuh7vka

Beginner2022-04-01Added 13 answers

cos3xsin3x=(cosxsinx)(cos2x+sinxcosx+sin2x)
Recall that cos2x+sin2x=1 and sin2x=2sinxcosx. Then
cos3xsin3x=(cosxsinx)(1+sin2x2)
So
cos3xsin3xcosxsinx=(cosxsinx)(1+sin2x2)cosxsinx
=2+sin2x2

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