(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Required to prove that (Sin[A] Sin[2 A] + Sin[3 A] Sin[6 A]) / (Sin[A] Cos[2 A] + Sin[3 A] Cos[6 A]) is identicle to tan[5A]

2. Relevant equations

the factor formulae must probably be used.

3. The attempt at a solution

I tried using the double angle identities and triple angle identies on top ie i was left with:

sinA 2sinAcosA + (3sinA - 4sin^3A)(3sinA - 4sin^3A + 3sinA - 4sin^3A)

then by simplifying i got:

2sin^2A(cosA + 9 - 24sin^2A + 16sin^4A)

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# Trigonometric Proofs with factor formulae

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