Mention the concepts in these lessons discussed:The Circle and its Parts, Relationships between Chords and Arcs, Properties of Central and Inscribed Angles and Intersecting Chords and their Properties and the calculations that took place in the logo (Its in the picture).

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.

step-by-step explanation:

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. ∠bac and ∠bca are the base angles of the triangle picture on the left. the vertex angle is ∠abc

probably .5

i can on others if necessary.