D and E are the mid-points of the sides AB and AC respectively of . DE is produced to F. To prove that CF is equal and parallel to DA, we need an additional information which is
(A)
(B) AE = EF
(C) DE = EF
(D)
Answer: (C) DE = EF
Solution.
Let us draw the figure according to question.
AE = EC {E is the mid-point of AC}
Let DE = EF
{vertically opposite angles}
{by SAS congruence rule}
{by CPCT rule}
{by CPCT}
Hence,
\ We need DE = EF.
Hence option C is correct.