Final answer:
A star at the top right corner of the H-R diagram would likely be significantly larger than the Sun, with a radius around fifty times that of the Sun, and would also be substantially larger than a typical white dwarf.
Step-by-step explanation:
The question is asking to calculate the radius of a star that is at the top right of the H-R diagram and compare it to the radius of the Sun and a typical white dwarf. The provided hints indicate calculating star radii using luminosity and temperature, assuming blackbody radiation.
A star at the top right corner of the H-R diagram such as a supergiant would typically have a radius that is much larger than the Sun's. From the most common properties of stars in this region of the H-R diagram, we can infer a radius more in line with option b) fifty times the Sun’s radius, but the answer could vary greatly depending on the specific star.
Comparing this to the radius of a white dwarf, we can reference a typical white dwarf being much smaller than the Sun’s radius, suggesting that a star with a radius fifty times that of our Sun would be substantially larger than that of a typical white dwarf.