Given : In a ΔABCl is a straight line passing through the vertex A. BM⊥ l and CN ⊥ l.L is the mid point of BC
To prove : LM = LN
Construction : Draw OL⊥l
Proof :
If a transversal make equal intercepts on three or more parallel lines, then any other transversal intersecting them will also make equal intercepts.
BM⊥l,CN ⊥l and OL ⊥l.
∴BM||OL||CN
Now, BM |OL|| CN and BC is the transversal making equal intercepts i.e., BL = LC.
∴ The transversal MN will also make equal intercepts.
⇒OM=ON
In ΔLMO and ΔLNO,