# Hyperbolas.

• December 12th 2011, 04:56 PM
Hyperbolas.
I know how to write the equation of a hyperbola with its two branches (i.e. x^2/a^2-y^2/b^2=1 or vice versa), but can you write the equation of just one branch of the hyperbola? Would it just be the equation of a parabola?

I know you could restrict the domain for those with horizontal transverse axes, but what about for vertical or in general?
• December 12th 2011, 06:04 PM
pickslides
Re: Hyperbolas.
Your hyperbola equation is centred at (0,0) so you can restrict the domain as x>0 or x<0.
• December 12th 2011, 07:01 PM
O.k, you require a hyperbola that opens up top and bottom, which is $\frac{y^2}{a^2}-\frac{x^2}{b^2}=1$ which is also centred at the origin, you can restrict $y>0$
And, in fact, for y> 0, you can solve for y: $y= a\sqrt{1- \frac{x^2}{b^2}}$.