Question

Найдите Найдите sinα , если cosα=0,6 и π<α<2π

Answer 1

$sin^2 alpha+cos^2 alpha=1; pi<alpha<2pi;\ sin alpha=-sqrt {1-cos^2 alpha}=-sqrt{1-0.6^2}=0.8$

ответ: 0.8

Answer 2

$sin^{2}alpha=1-cos^{2}alpha\ |sinalpha|=sqrt{1-cos^{2}alpha}\ sinalpha=-sqrt{1-0.6^{2}}=-sqrt{1-0.36}=-sqrt{0.64}=-0.8$