Chapter 7: Triangles

Properties of Triangles

Isosceles Triangle

Theorem: Angles opposite to equal sides are equal Converse: If two angles equal, opposite sides are equal


Triangle Inequality

  1. Sum of any two sides > third side: a+b>ca + b > c
  2. Difference of two sides < third side
  3. Longer side opposite larger angle

Example

Can 3, 4, 8 form a triangle? 3+4=7<83 + 4 = 7 < 8No!

Can 5, 6, 9 form a triangle? 5+6=11>95 + 6 = 11 > 9 ✓ → Yes!