Geometric transformations:
- Translation: (x, y) → (x + h, y + k)
- Scaling: (x, y) → (a·x, b·y)
- Rotation: θ about origin: x′ = x cosθ − y sinθ, y′ = x sinθ + y cosθ
- Reflection x/y axes: X‑axis: (x, −y), Y‑axis: (−x, y)
- Reflection y=x: (x, y) → (y, x)
- Reflection y=mx: across arbitrary line y = m x