Problem 9 on Project Euler: https://projecteuler.net/problem=9
In this problem, you are asked to find three Pythagorean triples with a specified sum.
This is equivalent to solving a quadratic equation (the Pythagorean theorem) and a linear equation (sum of three variables is a constant).
This can be visualized as the intersection of a plane and a cone.
Project Eulerproject euler notes
Round 1: Problems 1-20
Round 2: Problems 50-70
Round 3: Problems 100-110
Round 4: Problems 500-510
Round 5: Problems 150-160
Round 6: Problems 250-260
Round 7: Problems 170-180