Question

cos 45 + cos 135 ,cum se calculeaza ?

Answer 1

cel mai simplu se rezolva asa:
cos45+cos(90+45)=
$\frac{ \sqrt{2} }{2}$+cos90cos45-sin90sin45=
[tex] \frac{ \sqrt{2} }{2} +(0* \frac{ \sqrt{2} }{2} -1* \frac{ \sqrt{2} }{2}) = \frac{ \sqrt{2} }{2} +(- \frac{ \sqrt{2} }{2}) =0