Question

Найти tg a , если tg (a/2) =2

Answer 1

$tg alpha = frac{2tg frac{ alpha }{2} }{1-tg ^{2} frac{ alpha }{2} } = frac{2*2}{1-2 ^{2} }= frac{4}{-3} =-1 frac{1}{3}$