# Simson Line
Let(A = [-x1,0], B = [x1,0], C = [x2,x3], D = [x4,x5], P = [x4,0],
    Q = [x6,x7], H = [x8,x9], M = [x10,x11]):
SimsonLine := Theorem(
    [arbitrary(A,B,C), oncircle(A,B,C,D), perpfoot(D,P,A,B,P), 
     perpfoot(D,Q,A,C,Q), orthocenter(A,B,C,H), midpoint(D,H,M)], 
    collinear(P,Q,M), [x5, x6, x7, x8, x9, x10, x11] );
