TeX source:
\large\rho\left(A,B/C\right)=\Large\frac{\rho\left(A,B\right)-\rho\left(A,C\right)\rho\left(B,C\right)}{\sqrt{1-\rho\left(A,C\right)^{2}\sqrt{1-\rho\left(B,C\right)^{2}}}}