Proofs involving isosceles triangles often require special consideration because an isosceles triangle has several distinct properties that do not apply to normal triangles.(More about triangle types) Therefore, when you are trying to prove that two triangles are congruent, and one or both triangles, are isosceles you have a few theorems that you can use to make your life easier.
Isosceles Triangle
An isosceles triangle has two congruent sides and two congruent angles. The congruent angles are called the base angles and the other angle is known as the vertex angle. $$ \angle $$BAC and $$ \angle $$BCA are the base angles of the triangle picture on the left. The vertex angle is $$ \angle $$ABC
Isosceles Triangle Theorems
The Base Angles TheoremIf two sides of a triangle are congruent, then the angles opposite those sides are congruent.
Converse of the Base Angles TheoremThe converse of the base angles theorem, states that if two angles of a triangle are congruent, then sides opposite those angles are congruent.
Proof 1
Proof 2

Theorems and Postulates for proving triangles congruent
 Hypotenuse Leg Theorem
 Side Side Side
 Side Angle Side
 Angle Side Angle
 Angle Angle Side
 isosceles triangle proofs
 CPCTC
 indirect proof
 quiz on all theorems/postulates
 Images
 Free Math Printable Worksheets
 Worksheets & Activities on Triangle Proofs