- Right triangle: a² + b² = c² (c = hypotenuse)
- Special triangles: 3-4-5, 5-12-13, 8-15-17
- 45-45-90: legs = x, hypotenuse = x√2
- 30-60-90: short = x, long = x√3, hyp = 2x
- Isosceles triangle: 2 equal sides, 2 equal base angles
- Equilateral: all sides equal, all angles = 60°
Pythagorean Theorem
a² + b² = c²
Area of Triangle
A = ½ × base × height
Example
Legs = 6 and 8. Find hypotenuse.
c = √(36 + 64) = √100 = 10