aplic formula
sin a+sinb=2sin (a+b)/2*cos(a-b)/2
deci avem
2sin (2x+225+2x-45)/2*cos(2x+225-2x+45)/2=
2sin (4x+180)/2*cos 270/2=
2 sin (2x+90)*cos 135=
dar cos 135=-rad2/2
2*(-rad2/2)*sin (2x+90)=
-rad 2*sin (2x+90)
rezolvam sin(2x+90)=sin 2x*cos90+cos2x*sin 90=cos2x
cos90=0
sin90=1
deci rezultat final -rad2 *cos2x
