Question

Упростить 2tg 5"/ (1-tg^2 5")

Answer 1

$frac{2tg5}{1-tg^{2}5} = frac{2sin5}{cos5}*frac{1}{1-frac{sin^{2}5}{cos^{2}5}}= frac{2sin5}{cos5}*frac{1}{frac{cos^{2}5-sin^{2}5}{cos^{2}5}}=frac{2sin5}{cos5}*frac{cos^{2}5} {cos10}=$$frac{sin10}{cos10}=tg10$