sidesAs given by the question
There are given that ;
Now,
From the properties of an isosceles triangle, we also know that in an isosceles triangle, the altitude from the apex angle that bisects the base and the apex angle
So,
According to the question and also properties of an isosceles triangle
There are two equal side and the two angles opposite to the equal sides are equal and one line of symmetry.
So, we can say that triangle ABE is isosceles.
Hence, proved.