Given: △ABC, AD bisects ∠BAC, CE∥DA meets AB produced at E
To prove: ACE is an Isosceles triangle
Since, AD bisects ∠BAC
∠BAD=∠DAC
Now, AD∥CE
∠BAD=∠AEC (Corresponding angles)
and, ∠DAB=∠ACE (Alternate angles)
Thus, ∠AEC=∠ACE=∠BAD=∠DAC
In △ACE,
∠AEC=∠ACE
thus, AC=AE (Sides opposite to equal angles are equal)
Hence, △ACE is an Isosceles triangle.