If I am told that triangle CDE is isosceles, and a picture that tells me that CD is congruent to ED, Can I conclude angle C = angle E to the def of isosceles triangles
If I am told that triangle CDE is isosceles, and a picture that tells me that CD is congruent to ED, Can I conclude angle C = angle E to the def of isosceles triangles
You can conclude that, but it's not for the reason you stated. The theorem you want to reference is :
"If two sides of a triangle are congruent, then the angles opposite those sides are congruent."