The Event Horizon Telescope (EHT) recently observed the shadow of M 87* (the supermassive black hole, of about 6 billion solar masses, at the center of the giant elliptical galaxy M87, which is about 55 Mly away). If the observations were made at the radio wavelength of 1.3 mm & were at the diffraction limit for angular resolution at about 50 micro-arcseconds, about what was the distance between EHT’s component telescopes?