[tex]\boxed{cos\,60^o = sin(90^o - 60^o)=sin \,30^o} \\ \\
cos^230^o + cos^260^o + cos^245^o = \\
= \underbrace{cos^230^o + sin^230^o}_{=1} + (~\underbrace{cos45^o}_{= \frac{ \sqrt{2}}{2} }~)^2 = \\ \\
= 1 + \left( \frac{ \sqrt{2} }{2} \right)^2 = 1 + \frac{2}{4} =1 + \frac{1}{2} = \frac{3}{2} = \boxed{\boxed{1,5}}[/tex]
