7th Grade · Geometry
Proportional
7.G.A.1
Definition
Two figures are proportional if all pairs of corresponding sides have the same ratio (scale factor). Proportional figures have the same shape but different sizes.
Examples
- Sides 6/3, 8/4 both equal 2 — proportional, scale factor 2.
- Sides 3,4,5 vs 6,7,10 give ratios 2, 1.75, 2 — not equal, NOT proportional.
Key rule
All corresponding sides must be in the same ratio AND corresponding angles equal.
Memory hook
Same shape, same ratio, different size.