k2sin(p/4+y)=k2
sin(p/4+y)=1
p/4+y=p/2+2pn
y=p/2-p/4+2pn y=p/4+2pn
2sin(2x)cos(-x)=0
sin(2x)cos(-x)=0
sin(2x)cos(x)=0
sin(2x)=0 ; cos(x)=0