Question
Prove that:
$\cos^2 30^\circ - \sin^2 30^\circ = \cos 60^\circ$
$\cos^2 30^\circ - \sin^2 30^\circ = \cos 60^\circ$
✓
Answer
$\left(\frac{\sqrt{3}}{2}\right)^2-\left(\frac{1}{2}\right)^2$
$=\frac{3}{4}-\frac{1}{4}$
$=\frac{2}{4}$
$=\frac{1}{2}$
$=\cos 60^{\circ}$
$=\frac{3}{4}-\frac{1}{4}$
$=\frac{2}{4}$
$=\frac{1}{2}$
$=\cos 60^{\circ}$
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