Cześć!
[tex]\mathrm{sin^2(15^{\circ}) + cos^2(30^{\circ}) + sin^2(75^{\circ}) + cos^2(60^{\circ})} =\\\\ \mathrm{=cos(90^{\circ}-15^{\circ}) + cos^2(30^{\circ}) +sin^2(75^{\circ})+sin^2(90^{\circ}-60^{\circ})} = \\\\= \mathrm{cos^2(75^{\circ})+sin^2(75^{\circ})+sin^2(30^{\circ}) + cos^2(30^{\circ}) = 1+1=2}[/tex]
Pozdrawiam!
