Coordinate Geometry Key Formulas Distance = √((x₂-x₁)² + (y₂-y₁)²) Midpoint = ((x₁+x₂)/2, (y₁+y₂)/2) Lines Slope: m = (y₂-y₁)/(x₂-x₁) Point-slope: y - y₁ = m(x - x₁) Parallel lines: same slope Perpendicular lines: slopes are negative reciprocals (m₁ × m₂ = -1) SAT Applications Distance between two points Finding the midpoint Equation of a line through two points Identifying parallel/perpendicular lines from equations