how much is a in this hyperbola equation? we were given by our teacher today this equation: $(y^2/9)-(x^2/16)=1$ How much is a in this equation according to hyperbola equation?

In this equation the $y$ axis is along the vertical center of the symmetry of the hyperbola. So it can be written as 
$$
\frac{y^2}{a^2}-\frac{x^2}{b^2}=1
$$
so $a=3, b=4$
