> Let ABCD be a parallelogram such that AB=3DDC=3D10, and > AD=3DBC=3D6, > and angle(BAD)=3D60=C2=B0. Let H1,H2 be the orthocenters of > triangles ABD and CDB respectively. Determine the > distance between H1 and H2. >=20 > Best regards, > Avni

Even the incenter I1 is concyclic with C,D,B, see attachment.