sin(pi/2+x)-cos(pi+x)+1=0
cosx+cosx=-1
2cosx=-1
c0sx=-1/2
x=+-arccos(-1/2)+2pi n
x=+-2pi/3 +2pi n, neZ
sin(pi/2+x)-cos(pi+x)+1=0
cosx+cosx=-1
2cosx=-1
c0sx=-1/2
x=+-arccos(-1/2)+2pi n
x=+-2pi/3 +2pi n, neZ