beginfig(0); radius := 50; pickup pencircle scaled 2; path p; path s, second; z0 = (0, radius); z1=((x0+x2)/2,y0+radius); z2 = (x1+radius,y0); z3 = (x1,y0-radius); p := z0..z1..z2..z3..cycle; fill p withcolor 0.5blue; draw p withcolor white; clearxy; z0 = (xpart point 0.5 of p, 0.5radius); z1 = (xpart point 1.5 of p, y0); s:=z0{dir +45}..{dir -45}z1; draw s withcolor white; second:=s scaled 0.5 shifted (0,20) rotated 90; draw second withcolor white; endfig; end