Geometry · Foundation · 7 min
Triangle congruence
Congruent triangles have the same shape and size, even when they face different directions.
WHAT HAPPENS IF…Does rotating the copy change its area?
Loading the mathematical model…
Place a side of length a on the horizontal axis. A second side of length b at included angle C fixes the third vertex. The law of cosines then fixes the remaining side. Rigid motions preserve distances, so the rotated copy is congruent for every rotation shown.
A detail that matters
Two sides and an angle that is not between them can produce ambiguous triangles; SAS requires the included angle.
Keep the connection going
More geometry ↗