the Side Splitter Theorem is a theorem which can be proven when it comes to Triangle Similarity. It states:
"If a line is parallel to one side of a triangle and intersects the other two sides then it divides those sides proportionally."
Lines BD and CE are paarallel in triangle △CAE, so this states sides AB and AD are proportional to sides BC and DE.
Parnet apge: Math (list pag)