The vertices of the hyperbola are the x-intercepts of the hyperbola
The equation of the hyperbola is [tex]\frac{y^2}{400} -\frac{x^2}{81} = 1[/tex]
The equation of a hyperbola is represented as:
[tex]\frac{(y - k)^2}{a^2} -\frac{(x - h)^2}{b^2} = 1[/tex]
The vertices are (20,0) and (-20,0).
So, the center of the hyperbola is:
(h,k) = (0,0).
Also, we have:
a = 20
This gives
[tex]\frac{(y - 0)^2}{a^2} -\frac{(x - 0)^2}{b^2} = 1[/tex]
Evaluate
[tex]\frac{y^2}{a^2} -\frac{x^2}{b^2} = 1[/tex]
Substitute 20 for a
[tex]\frac{y^2}{20^2} -\frac{x^2}{b^2} = 1[/tex]
[tex]\frac{y^2}{400} -\frac{x^2}{b^2} = 1[/tex]
The length of the conjugate axis is:
l = 18 units
So, we have:
[tex]b = \frac{18}2 = 9[/tex]
The equation becomes:
[tex]\frac{y^2}{400} -\frac{x^2}{9^2} = 1[/tex]
[tex]\frac{y^2}{400} -\frac{x^2}{81} = 1[/tex]
Hence, the equation of the hyperbola is [tex]\frac{y^2}{400} -\frac{x^2}{81} = 1[/tex]
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