Corollary 1 of Theorem 28 gives —

• a$\dfrac{AB}{AD} = \dfrac{AC}{AE}$
• b$\dfrac{AD}{AB} = \dfrac{AE}{EC}$
• c$\dfrac{AB}{DB} = \dfrac{AE}{AC}$
• d$\dfrac{AB}{AD} = \dfrac{AC}{CE}$