Answer :
[tex]A=C(1-S^2)[/tex]
The given equation express A in function of C and S. To express the equation as S in terms of A and C you need to solve the variable S:
-Divide both sides of the equation into C
[tex]\begin{gathered} \frac{A}{C}=\frac{C(1-S^2)}{C} \\ \\ \frac{A}{C}=1-S^2 \\ \\ \end{gathered}[/tex]- Substract 1 in both sides of the equation:
[tex]\begin{gathered} \frac{A}{C}-1=1-1-S^2 \\ \\ \frac{A}{C}-1=-S^2 \end{gathered}[/tex]-Multiply both sides of the equation by -1:
[tex]\begin{gathered} (-1)(\frac{A}{C}-1)=(-1)(-S^2) \\ -\frac{A}{C}+1=S^2 \end{gathered}[/tex]-Take square root of both sides of the equation:
[tex]\begin{gathered} \sqrt[]{(-\frac{A}{C}+1)}=\sqrt[]{S^2} \\ \\ \sqrt[]{-\frac{A}{C}+1}=S \end{gathered}[/tex]Then, the equation that express S in terms of A and C is:
[tex]S=\sqrt[]{-\frac{A}{C}+1}[/tex]