Question

Să se calculeze cos² 60°+ sin² 120°.​

Answer 1

Răspuns:

$\cos(60) = \frac{1}{2}$

${ \cos(60) }^{2} = \frac{1}{4}$

$\sin(120) = \sin(180 - 60) = \sin(60) = \frac{ \sqrt{3} }{2}$

${ \sin(60) }^{2} = \frac{3}{4}$

${ \cos(60) }^{2} + { \sin(120) }^{2} = \frac{1}{4} + \frac{3}{4} = 1$