Math
Isosceles triangle theorem.
Definition
A theorem stating that if two sides of a triangle are congruent (equal in length), then the angles opposite those sides are also congruent. The converse is also true: if two angles are congruent, the sides opposite them are congruent.
Examples
Real-world.
- 1 In a triangle with two sides of length 5, the base angles must be equal
- 2 An equilateral triangle is a special case where all three sides and angles are equal
- 3 Finding a missing angle in a triangle where two sides are marked congruent
Key Fact
If AB ≅ AC, then ∠B ≅ ∠C (base angles are congruent).