# How to Write the Equation of a Hyperbola in Standard Form

Coming up next: The Parabola: Definition & Graphing

### You're on a roll. Keep up the good work!

Replay
Your next lesson will play in 10 seconds
• 0:02 A Hyperbola
• 2:16 The Problem
• 4:01 The Center, Vertices & Foci
• 5:40 Writing the Equation
• 6:23 Lesson Summary

Want to watch this again later?

Timeline
Autoplay
Autoplay
Speed

#### Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Yuanxin (Amy) Yang Alcocer

Amy has a master's degree in secondary education and has taught math at a public charter high school.

When it comes to equations in algebra, there is most always a standard form that provides us with useful information. Watch this video lesson to learn how to write the standard form equation of a hyperbola by using information about the hyperbola.

## A Hyperbola

When it comes to algebra, we have equations and then we have standard form equations. Equations in standard form are those equations that are written in such a way so that we can see our useful information by just looking at the numbers. In this video lesson, we're going to be talking about the standard form equation of a hyperbola.

A hyperbola is a shape that looks like two arcs back to back with each other. You get this kind of shape when you stack two ice cream waffle cones on top of each other so that their tips are touching in the middle and then you cut it in a way so that you go through both cones. Just like with hyperbolas, you can stack your cones upright or you can lay them on the side. If your cones are upright, then your hyperbola will open up and down. If your cones are laid on a flat surface, then your hyperbola opens to the left and right. Because we have these two different directions that our hyperbola can be, we have two different forms of our standard form equation, one for the hyperbola that opens up and down and another for the hyperbola that opens sideways.

The standard form of a hyperbola that opens sideways is (x - h)^2 / a^2 - (y - k)^2 / b^2 = 1. For the hyperbola that opens up and down, it is (y - k)^2 / a^2 - (x - h)^2 / b^2 = 1. Notice that the x appears first for the hyperbola that opens sideways and the y appears first for the hyperbola that opens up and down. So you can link this with the axis that the cones are on. If it's the x-axis, the hyperbola opens sideways and the x appears first. If it's the y-axis, then the hyperbola opens up and down and the y appears first. Notice also that the h always appears with the x and the k with the y. And the a always comes before the b as it does in the alphabet. The letters h, k, a and b are there to provide us with useful information about our hyperbola, as we will see.

## The Problem

When you are given a problem asking you to write the standard form equation of a hyperbola, the problem will need to provide you with just a few bits of information. The information that you need to know is the location of the center of the hyperbola, the location of its vertices (the tips of the arcs of the hyperbola) and the location of the foci (the point in each arc where the ratio of the distance from any point on the arc to this focus point to the distance from this same point on the arc to a straight line is always the same).

When written in standard form, our hyperbola equation tells us that our center is located at (h, k) and that our vertices are a spaces away from the center in both directions. For hyperbolas that open up and down, the vertices are a spaces above and below the center. For hyperbolas that open sideways, the vertices are a spaces to the left and right of our center. The location of the foci is c spaces away from the center, where c^2 = a^2 + b^2. Just like for the vertices, if the hyperbola is upright, then the foci are located c spaces above and below the center, and if the hyperbola is sideways, then the foci are located c spaces to the left and right of the center.

Let's look at an example now. Our problem asks us to write the standard form equation of a hyperbola with a center located at (1, 2), with vertices located at (-2, 2) and (4, 2) and with foci located at (-4, 2) and (6, 2).

## Centers, Vertices and Foci

With this information, we can go ahead and write our complete standard form equation. The first thing we see is that our center is at (1, 2) so that means our h is 1 and our k is 2. So far, so good! We have two of our letters down. We just need a and b now.

To unlock this lesson you must be a Study.com Member.

### Register to view this lesson

Are you a student or a teacher?

#### See for yourself why 30 million people use Study.com

##### Become a Study.com member and start learning now.
Back
What teachers are saying about Study.com

### Earning College Credit

Did you know… We have over 160 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.