Home › NY Regents Geometry › Mathematics › The Hyperbola › A hyperbola has vertices at (2, -3) and (10, -3)…
A hyperbola has vertices at (2, -3) and (10, -3) and foci at (0, -3) and (12, -3). What is b squared?
Ab squared is 52
Bb squared is 16
Cb squared is 36
Db squared is 20
Answer & Solution
Correct answer: D. b squared is 20
1. The vertices and foci all share the y-coordinate negative 3, so the transverse axis is parallel to the x-axis.
2. The center is the midpoint of the vertices, which is (6, -3).
3. The transverse axis runs from x equal to 2 to x equal to 10, so 2a is 8 and a is 4.
4. That gives a squared equal to 16.
5. Each focus sits 6 units from the center at x equal to 6, so c is 6 and c squared is 36.
6. Rearranging c squared equals a squared plus b squared gives b squared equal to 36 minus 16.
7. So b squared is 20.
8. Answering 52 adds the two squares instead of subtracting them.
9. Answering 16 stops at a squared and never reaches b.
10. Answering 36 reports c squared, which measures the foci rather than the co-vertices.
_Source: OpenStax College Algebra (CC BY 4.0), Ch 8 "Analytic Geometry", section 8.2 The Hyperbola_
Related questions
How can the asymptotes of a hyperbola be sketched from its central rectangle?A hyperbola centered at the origin has a squared equal to 64 and b squared equal to 36. HoWhich axis of a hyperbola has the two vertices as its endpoints?For every point on a hyperbola, which quantity built from the two foci stays constant?