import solids;
size(7.5cm,0);

currentprojection=orthographic(3,1,2);

triple vectaxe=(1,0,0);
transform3 r=rotate(-90,vectaxe);
triple pA=(1,0,1), pB=(4,0,1), pC=(1,0,4);
path3 tri=pA--pB--pC--cycle;
path3 trip=r*tri;

draw(tri^^trip);

limits(O,X+Y+Z);
xaxis3(Label("$x$",1),Arrow3);
yaxis3(Label("$y$",1),Arrow3);
zaxis3(Label("$z$",1),Arrow3);

pen dotteddash=linetype("0 4 4 4"),
    p2=.8bp+blue+dotted;
draw((-1,0,0)--(4,0,0),red+dotteddash);
draw(arc((pA.x,0,0),pA,r*pA,CCW),p2,Arrow3); // CCW=true=counterclockwise
draw(arc((pB.x,0,0),pB,r*pB,CCW),p2,Arrow3); // CW=false
draw(arc((pC.x,0,0),pC,r*pC,CCW),p2,Arrow3);