Write a two-column proof for the following: In the figure AKMJ and BMJK are parallelograms. If KJ = KM, then ABC is isosceles

Question

Answer 1

I will not give you every step of the 2 column proof, but if you follow what I give you, you should be able to write it completely.

Because of the parallelograms and KJ=KM, triangles AJK,KJM and MBK are all isosceles and congruent.

That makes angles JAK and KBM equal (corresponding parts of congruent triangles)

Therefore ABC is isosceles.