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Question
Prove that `(sin 4x + sin 2x)/(cos 4x + cos 2x)` = tan 3x
Solution
`(sin 4x + sin 2x)/(cos 4x + cos 2x)` = `(2sin((4xx + 2x)/2) * cos((4x - 2x)/2))/(2cos((4x + 2x)/2) * cos((4x - 2x)/2))`
= `(sin 3x * cos x)/(cos 3x * cos x)`
= `(sin 3x)/(cos 3x)`
= tan 3x
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