Use the fact that the orbit of a planet about the Sun is an​ ellipse, with the Sun at one focus. The aphelion of a planet is its greatest distance from the​ Sun, and the perihelion is its shortest distance. The mean distance of a planet from the Sun is the length of the semimajor axis of the elliptical orbit. See the illustration. The mean distance of planet A from the Sun is 86 million miles. If the aphelion of planet A is 88.5 million​ miles, what is the​ perihelion? Write an equation for the orbit of planet A around the Sun.