Чи існуе кут $\alpha,$ де $0^\circ⩽α⩽180∘,$ для якого:
1) $\cos\alpha=\frac{2}{5};$
2) $\sin\alpha=-\frac{2}{5};$
3) $\cos\alpha=-\frac{2}{5};$
4) $\sin\alpha=\frac{2}{5};$
5) $\cos\alpha=1{,}2;$
6) $\sin\alpha=1{,}2?$
1) $\cos\alpha=\frac{2}{5};$
2) $\sin\alpha=-\frac{2}{5};$
3) $\cos\alpha=-\frac{2}{5};$
4) $\sin\alpha=\frac{2}{5};$
5) $\cos\alpha=1{,}2;$
6) $\sin\alpha=1{,}2?$