u = 0.7cm; beginfig(1); pair A, B, C, M, N, P, Q; A=(0,0)*u; B=(-0.75,-3)*u; C=(1.5,-3)*u; M=(-0.5,-2)*u; N=(1,-2)*u; P=(0.25,1)*u; Q=(-0.5,1)*u; draw (0.25,1)*u--(-1,-4)*u withpen pencircle scaled 1pt; draw (-1/2,1)*u--(2,-4)*u withpen pencircle scaled 1pt; draw (-1,-2)*u--(1.5,-2)*u withpen pencircle scaled 1pt; draw (-1,-3)*u--(2,-3)*u withpen pencircle scaled 1pt; label.lft("A",A); label.urt("C",C); label.ulft("B",B); label.ulft("M",M); label.urt("N",N); label.rt("(d)",P); label.lft("(d')",Q); endfig; end