ABC is an isosceles triangle because the triangle has two congruent sides.
Steps to prove that ∆ ABC is an isosceles triangle?
To prove that ∆ ABC is an isosceles triangle, the following steps should be taken as follows;
Given;
Line BE≈ line BD
Line AD ≈ line CE
∠BED ≈ ∠BDE . This is because corresponding parts of congruent triangles are congruent too.
∆ADB ≈ ∆ CEB . This obeys the side -angle-side rule.
Line AB ≈ Line BC . This shows transitive property.
Therefore, ABC is an isosceles triangle because the triangle has two congruent sides.