Jack claims that the two triangles below are congruent because they are isosceles triangles and we know 2 sides are congruent. Explain the error in his reasoning.
The error in Jack's reasoning is that being an isosceles triangle does not guarantee that the triangles are congruent. An isosceles triangle only guarantees that at least two sides are congruent, but it does not guarantee that the remaining angles or sides are congruent as well. In order to prove that two triangles are congruent, all corresponding sides and angles must be congruent.
