Question

Tg a/2=? если 180<a<270 и tga=4/3

Answer 1

$tg(a) = frac{sin(a)}{cos(a)} = frac{2sin (frac{a}{2} )cos (frac{a}{2})cos}{cos^2( frac{a}{2} ) - sin^2( frac{a}{2} ) } \ \ frac{2tg( frac{a}{2} )}{1-tg^2( frac{a}{2}) } = frac{4}{3} \ tg(a) = -2$