Given problem;
A = [tex]\pi[/tex] r²
Solve for π;
To solve for π implies that we make it the subject of the expression.
So;
A = π r²
Now multiply both sides by [tex]\frac{1}{r^{2} }[/tex]
So;
A x [tex]\frac{1}{r^{2} }[/tex] = [tex]\pi[/tex] x r² x [tex]\frac{1}{r^{2} }[/tex]
r² cancels out from the right side and leaves only π;
π = [tex]\frac{A}{r^{2} }[/tex]
So [tex]\pi = \frac{A}{r^{2} }[/tex]