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Examining the Standard Equation
of a Hyperbola Centred at (h, k)

The standard equation of a hyperbola centred at the origin is x2/ a2 - y2/ b2 = 1 when the hyperbola opens left and right, and -x2/ a2 + y2/ b2 = 1 when the hyperbola opens up and down.
Notice that these equations are similar to the standard equation of an ellipse centred at the origin:
x2 +y2 = 1.
a2 b2
When we translated an ellipse from being centred at the origin to being centred at any other point (h, k), the standard equation became:
(x - h)2 +(y - k)2 = 1.
a2
b2
When the centre of a hyperbola is translated to a point (h, k), the standard equation changes in the same way as the standard equation for an ellipse.
The standard equation for a hyperbola centred at (h, k) and opening horizontally is:
(x - h)2 -(y - k)2 = 1.
a2
b2

The standard equation for a hyperbola centred at (h, k) and opening vertically is:
- (x - h)2 +(y - k)2 = 1.
a2
b2
The following activities will explore the standard equation of a hyperbola centred at a point (h, k). Note that when you translate the red hyperbola, a faint black hyperbola will remain in the original position. It is only a reference that is there to aid you in understanding how it was translated.

(x - h)2 -(y - k)2 = 1    or    - (x - h)2 +(y - k)2 = 1
a2
b2
a2
b2

Now, let's look at the how varying a and b effect the graph of a hyperbola centered at (h, k).

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