X-ray pulses from Cygnus X-1,a celestial x- ray source, have been recorded during high- altituderocket flights. The signals can be interpreted as originating whena blob of ion- ized matter orbits a black hole with a period of 5.25 ms. If the blob were in a circular orbit about a black holewhose mass is 20.7 times the mass of the Sun, what is the orbitradius? The value of the gravitational constant is 6.67259 ×10−11 N · m2/kg2 and mass of the Sun is 1.991 ×1030 kg. Answer in units of km.