Question

Найдите tgy, если tg(x+y)=5 tgx=3

Answer 1

$tg(x+y)=frac{tgx+tgy}{1-tgx*tgy}\\5=frac{3+tgy}{1-3*tgy}\\5(1-3tgy)=3+tgy\5-15tgy=3+tgy\5-3=15tgy+tgy\2=16tgy\\frac{2}{16}=tgy\\frac{1}{8}=tgy\\tgy=frac{1}{8}\tgy=0,125$