Respostas

2013-04-13T20:53:59-03:00

 tg(x + π/4) = -cotg(x)
tg(x) = -1/tg(x + π/4)
 tg(2x) = 2tg(x)/(1 - tg²(x) = (-2/tg(x + π/4))/(1 - 1/tg²(x + π/4)) =
 tg(2x) = -2tg(x + π/4)/(tg²(x + π/4) - 1)

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