Question

Solve: ${\cos }^2{30}^0+{\cos }^{2}x=1$

Answer 1

${\cos }^{2}30+{\cos }^{2}x=1$

$(\frac{\sqrt{3}}{2}{)}^2+{\cos }^{2}x=1$

${\cos }^{2}x+\frac{3}{4}=1$

${\cos }^{2}x=\frac{1}{4}$

$\cos x=\frac{1}{2}$

$\cos x=\cos 60$

$x={60}^{\circ }$