Question

Как решить?

sin$frac{ 6pi }{5}$×tg$frac{7 pi }{3}$

Answer 1

$sin frac{6pi}{5}cdot tgfrac{7pi }{3 } =sin(pi +frac{pi}{5})cdot tg(2pi+frac{pi}{3})=-sinfrac{pi}{5}cdot tgfrac{pi}{3}=[; frac{ pi}{5}=36^circ ]=\\=- frac{sqrt{10-2sqrt5}}{4} cdot sqrt3=- frac{sqrt{30-6sqrt5}}{4}$