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# I need help with math trigonometry?

If sin (2x=3/5) och 0<x<π/4. Solve for cosx cos3x(tanx + tan 3x)

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- ?Lv 73 months ago
cosx cos3x(tanx + tan 3x)= cos x cos 3x (sin x/cos x+sin 3x /cos 3x)

= cos x cos 3x/(cos x cos 3x)(sin x cos 3x +cos x sin 3x)= sin 4x

=2 sin 2x cos 2x= 2*3/5(sqrt(1-9/25))= 6/5 (+/- 4/5)=+/- 24/25

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