According to the question,
ΔABC with ∠A = 90o and
Since, ABC is an isosceles triangle,
We get,
AB = AC …(i)
Let ADEF be the square inscribed in the isosceles triangle ABC.
Then, we have,
AD = AF = EF = AD …(ii)
Subtracting equation (ii) from (i),
AB – AD = AC – AF
BD = CF
Now,
Considering ΔCFE and ΔEDB,
BD = CF
DE = EF
∠CFE = ∠EDB = 90o (Since, they are the side of a square)
ΔCEF ~ ΔBED (By SAS criteria)
Hence, CE = BE
Therefore, vertex E of the square bisect the hypotenuse BC.