In each of the following Exercises 10 to 20, find the equation for the ellipse that satisfies the given conditions: Vertices (± 6, 0), foci (± 4, 0)
The equation of the ellipse is .
Explanation
This question is from Exercise 10.3, which deals with finding equations of ellipses. The student needs to identify that since vertices and foci are both on the x-axis, the major axis is horizontal. Using the standard form x²/a² + y²/b² = 1, they calculate a from vertices and c from foci, then use the relationship c² = a² - b² to find b².
Solution Steps
Step 1: Since vertices (± 6, 0) and foci (± 4, 0) are on the x-axis, the equation is of the form , where a is the semi-major axis.
Step 2: From vertices (± 6, 0), we get a = 6, so a² = 36.
Step 3: From foci (± 4, 0), we get c = 4, so c² = 16.
Step 4: Using the relation c² = a² - b², we get: , therefore b² = 20.
Step 5: Substituting a² = 36 and b² = 20 in the standard equation: .