41 Halley's Comet Halley's comet travels in an ellipti-
cal orbit with a = 17.95 and b = 4.44 and passes
by Earth roughly every 76 years. Note that each
unit represents one astronomical unit, or 93 million
miles. The comet most recently passed by Earth
in February 1986. (Source: M. Zeilik, Introductory
Astronomy and Astrophysics.)
(a) Write an equation for this orbit, centered at (0,0)
with major axis on the x-axis.
(b) If the sun lies (at the focus) on the positive
x-axis, approximate its coordinates.
(c) Determine the maximum and minimum distances
between Halley's comet and the sun.