Question 8
Using converse of basic proportionality theorem, prove that the line joining the mid-points of any two sides of a triangle is parallel to the third side.
Given, ΔABC in which D and E are the mid points of AB and AC respectively such that AD=BD and AE=EC.
To Prove that DE || BC
Proof
D is the mid-point of AB (Given)
∴AD=DB
⇒ADBD=1...(i)
Also, E is the mid-point of AC (Given)
∴AE=EC
⇒AEEC=1.....(ii)
From equation (i) and (ii), we get
ADBD=AEEC, hence, DE || BC [By converse of Basic Proportionality Theorem]