Question

If a pebble is dropped into a pond in the shape of an ellipse at the location of one focus, the waves will converge at the location of the other focus. If the pond has a major axis of 34 feet and a minor axis of 16 feet, how far apart are the foci?
A. 15 feet
B. 18 feet
C. 30 feet
D. 60 feet

Answer 1

where: a is the length of the major axis and b is the length of the minor axis.

Thus, 

$c= \sqrt{34^2-16^2} = \sqrt{1156-256} = \sqrt{900} c=30 Therefore, the distance apart of the two foci is given by 2c=2(30)=60 feet$

Answer 2

The answer is 60 feet