Question 490823
I am assuming you mean a congruent triangle.

A triangle is congruent to a second trianlge if all three corresponding angles are congruent and all three corresponding sides are congruent.

More formally, two sets of points are called congruent if, and only if, one can be transformed into the other by an isometry, i.e., a combination of translations, rotations and reflections.

Cleomenius.