Question

Помогите с номером 3

Answer 1

$cosa=-frac{3}{5}\1) sin^{2}a+cos^{2}a=1\ sin^{2}a=1-cos^{2}a\ sin^{2}a=1-frac{9}{25}=frac{16}{25}\ sina=+-sqrt{frac{16}{25} } =+-frac{4}{5} \ pi<n<3*pi/2 => sina=-frac{4}{5} \\\2) tga=frac{sina}{cosa}=-frac{4}{5}: -frac{3}{5}= frac{4}{5}* frac{5}{3}=frac{4}{3}\3) ctga=frac{1}{tga} =1:frac{4}{3}=frac{3}{4}$