LEARN PROVING THE TRIANGLE PROPORTIONALITY THEOREM
Triangle Proportionality Theorem: If a line is parallel to one side of a triangle and also intersects the other two sides, the line
divides the sides proportionally.
Given: AABC, DE intersects AB and AC, and DE || BC.
B
Prove:
AD AE
AB AC
E
2
COMPLETE THE PROOF
Reasons
Statements
A ABC is intersected by line DE
DE || BC
ABC - ADE
ACB - AED
.
AABC - SADE
AD AE
AB AC