a: \(\dfrac{EB}{FC}=\dfrac{BH^2}{AB}:\dfrac{CH^2}{AC}\)
\(=\dfrac{BH^2}{AB}\cdot\dfrac{AC}{CH^2}=\dfrac{AB^4}{AC^4}\cdot\dfrac{AC}{AB}=\dfrac{AB^3}{AC^3}\)
c: \(BC\cdot BE\cdot CF\)
\(=BC\cdot\dfrac{BH^2}{AB}\cdot\dfrac{CH^2}{AC}\)
\(=\dfrac{AH^4}{AH}=AH^3\)