The explosion of large stars causes a supernova. The remnants of a supernova explosion may lead to the formation of a highly magnetized and compact object called a magnetar. Magnetars are a type of neutron star. Magnetars are thought to be the source of some of the most energetic and powerful explosions in the universe such as gamma-ray bursts. Magnetars rotate about their axis at a rate of once every 9.0 s. Find the radius of its geosynchronous orbit. Consider the mass of magnetar is 2.78 × 10³⁰ kg.