Question

If two circles are congruent are the diameters the same lengh

Answer 1

Yes.
The definition of congruent circles is two circles with equal radii. Because the diameter is twice the radius, it is true that the diameters of two congruent circles are the same length.

Answer 2

Yes. congruent means same in length and shape. if 2 circles are congruent, they mean that they have the same diameters. if not then they're not congruent.