Question

From the given diagram, in which ABCD is a parallelogram, ABL is a line segment and E is mid-point of BC.

prove that : AL = 2DC

Answer 1

Given: ABCD is a parallelogram in which is the mid-point of BC.
We need to prove that 

Al =  AB+ BL                                          ... ( 4 )    
From (3) and (4), Al = AB + AB
⇒AL = 2AB
⇒AL = 2DC                    [ From ( 2) ]