Triangles on a Four-by-Four Grid
Consider the 16 points $(x, y)$ with $x, y \in \{0, 1, 2, 3\}$. How many triangles with positive area have all three vertices among these points? Give an integer.
Related problems & prerequisites
Worth solving first
- Inside the Triangle 4.0/10
- Lattice Points on a Circle 4.0/10
Source: Classic exercise in wide circulation; no traceable original source. Statement written for AxiomIQ.