How to get from one form to another

Question

I found this equation to be true, but I want to know how if I have the left form how the right one is got:

$$\displaystyle\frac{a^2}{a^2+b^2}=\frac {1}{1+\displaystyle\frac {b^2}{a^2}}.$$

Thanks in advance.

Answer 1

You have

$$\frac {a^2}{a^2+b^2}=\frac {\displaystyle\frac 1{a^2}\times a^2}{\displaystyle\frac 1{a^2}\times(a^2+b^2)}=\frac 1{1+\displaystyle\frac {b^2}{a^2}}.$$