Question

Найдите найдите sinα , если cosα=0,6 и π

Answer 1

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

ответ: 0.8

Answer 2

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