You learned the coordinate plane, distance formulas (Euclidean and Manhattan), the Pythagorean theorem, and area and perimeter calculations for rectangles, triangles, and circles.
You worked through three problems: valid triangle (checking triangle inequality), rectangle area (handling overlaps), and valid square (distance pattern validation). Each problem applied geometry formulas in a different way.
You now recognize when a problem needs geometry. You can compute distances, slopes, areas, and validate shapes. These skills show up in grid problems, collision detection, and spatial queries. Next section: we move beyond basic geometry into more advanced topics.