Math

Proportions in triangles.

Definition

When a line is drawn parallel to one side of a triangle, it divides the other two sides proportionally. This principle extends to angle bisectors, which divide the opposite side in the ratio of the adjacent sides.

Examples

Real-world.

  • 1 A midsegment is parallel to the third side and half its length
  • 2 If DE ∥ BC in triangle ABC, then AD/DB = AE/EC
  • 3 An angle bisector in a triangle with sides 6 and 9 divides the opposite side in ratio 6:9 = 2:3
Studied in

1 unit use this concept.