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

Prove: AE / CE = AB / CD

Click or touch to draw on the diagram
∠DAB =∠DCB
Substitution
∠AEB = ∠CED
AE / CE = AB / CD
△AEB ~ △CED
AA similarity
∠DAB=(1/2) * (arc DB) and ∠DCB=(1/2) * (arc DB)
Definition
Inscribed angle measures half its intercepted arc
Vertical angles are equal