Answer:
The required formula is [tex]b=\frac{4A}{\pi a}[/tex] .
Step-by-step explanation:
The given formula is
[tex]A=\frac{\pi ab}{4}[/tex]
Multiply both sides by 4.
[tex]A\times 4=\frac{\pi ab}{4}\times 4[/tex]
[tex]4A=\pi ab[/tex]
Divide both sides by πa.
[tex]\frac{4A}{\pi a}=\frac{\pi ab}{\pi a}[/tex]
[tex]\frac{4A}{\pi a}=b[/tex]
Therefore required formula is [tex]b=\frac{4A}{\pi a}[/tex] .