BM and CN are perpendiculars to a line passing through the vertex A of a triangle ABC. If L is the mid point of BC, prove that LM=LN.
Given: X is a straight line passing through the vertex A of ΔABC.BM⊥l and CN⊥X and L is the mid point of BC.
ML and NL are joined.
To prove : LM =LN
Construction : Draw OL⊥l
Proof : Consider two triangle ΔBLM and ΔCLN
∠BML=∠CNL=90∘
BL=LC as L is a mid point BC.
∠MLB=∠NLC as vertically opposite angles.
Therefore, ΔBLM≅ΔCLN.
Hence, LM=LN as corresponding sides of congruent triangles are equal