8th Grade · Geometry
Congruent
8.G.A.2
Definition
Having exactly the same size and shape. Two figures are congruent if a sequence of rigid motions maps one onto the other, making all corresponding parts equal.
Examples
- If △ABC ≅ △DEF, then AB=DE, BC=EF, CA=FD.
- Congruent means same size AND same shape; similar means same shape, possibly different size.
Key rule
A rigid motion (slide, flip, turn) maps congruent figures exactly onto each other.
Memory hook
Same size, same shape, exactly.