Răspuns:
[tex] \cos(60) = \frac{1}{2} [/tex]
[tex] { \cos(60) }^{2} = \frac{1}{4} [/tex]
[tex] \sin(120) = \sin(180 - 60) = \sin(60) = \frac{ \sqrt{3} }{2} [/tex]
[tex] { \sin(60) }^{2} = \frac{3}{4} [/tex]
[tex] { \cos(60) }^{2} + { \sin(120) }^{2} = \frac{1}{4} + \frac{3}{4} = 1[/tex]
