import solids;

currentprojection=orthographic(5,3,4);

size(7.5cm);

real a=6,b=3,c=2;

draw(box(O,(a,b,c)),green);
draw(shift(Z)*unitsquare3,2bp+blue);

limits(O,X+Y+Z);
xaxis3(scale(1.5)*Label("$\vec{\imath}$",1),1bp+red,Arrow3);
yaxis3(scale(1.5)*Label("$\vec{\jmath}$",1),1bp+red,Arrow3);
zaxis3(scale(1.5)*Label("$\vec{k}$",1),1bp+red,Arrow3);