Question

In the given figure, DE || AB and FE || DB. Prove that DC2 = CF . AC [CBSE 2007]

Answer 1

see the diagram that was missing from the question.

In ΔABC,  we have  CD/DA = CE/EB      as AB || DE
in ΔCDB,  we have  CF/FD = CE/EB     as  EF || BD

hence we get   CD/DA = CF/FD
=> Reciprocals:     DA/CD = FD /CF
=> Add 1 on both sides:     AC /CD = DC/CF

=>    DC^2 = CF * AC

Answer 2

here is ur answer guys