Given: Points C,E,B and A,E,D are collinear

Prove: AE / CE = AB / CD

Click or touch to draw on the diagram
Substitution
△AEB ~ △CED
AE / CE = AB / CD
∠DAB =∠DCB
∠DAB=$$\frac{1}{2}\overset{\large\frown}{DB}$$ and ∠DCB=$$\frac{1}{2} \overset{\large\frown}{DB}$$
Definition
∠AEB = ∠CED
AA similarity
Inscribed angle measures half its intercepted arc
Vertical angles are equal