Definition
Congruent figures
Congruent figures have exactly the same shape and size, even in different positions.
What it means
Imagine cutting out one figure. You may slide it, turn it, or flip it. If it can cover the other figure exactly, the two figures are congruent. Their matching side lengths and angle measures are equal.
Remember it
Slide, turn, or flip—never stretch—and the figures still match exactly.
Example
One rectangle measures 2 cm by 4 cm. Another measures 4 cm by 2 cm. Rotate the second rectangle a quarter turn and the two cover each other exactly, so they are congruent.
Watch for
A same-shaped figure that has been enlarged or reduced is similar, not congruent.
Common mix-up
Position and facing can differ; congruence depends on exact shape and size.
Exact meaning
Two plane figures are congruent when one can be mapped exactly onto the other by a sequence of rigid motions—translations, rotations, or reflections—without resizing or distorting it.