Explain, why
From the given figure, it is clear:
∠ABC = ∠FED (i)
Also,
∠BAC = ∠EFD (ii)
Therefore,
The two angles of ABC are equal to the two respective angles of FED
Also,
We know that:
Sum of interior angles of a triangle is equal to 180o
Hence,
The third angle of both the triangles will also be equal
Thus,
∠BCA = ∠EDF (iii)
Therefore,
From (i), (ii) and (iii)
FED
By AAA congruence criterion