Question

sin 2а + sin 6а
cos2x+cos6a Докажите, что = tg 3a.​

Answer 1

Объяснение:

$\displaystyle\\\frac{sin2\alpha +sin6\alpha }{cos2\alpha +cos6\alpha }=\frac{sin6\alpha +sin2\alpha }{cos6\alpha +cos2\alpha }=\frac{2*sin\frac{6\alpha +2\alpha }{2} *cos\frac{6\alpha -2\alpha }{2} }{2*cos\frac{6\alpha +2\alpha }{2}*cos\frac{6\alpha -2\alpha }{2} } =\\\\\\=\frac{sin4\alpha *cos2\alpha }{cos4\alpha *cos2\alpha } =\frac{sin4\alpha }{cos4\alpha }=tg4\alpha .$

Answer 2

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