Question 54
Find all quadruples $(a, b, c, d)$ of positive integers such that
$$
a^2 + b^2 = c^2 + d^2
$$
and such that $ac + bd$ is a divisor of $a^2 + b^2$.
$$
a^2 + b^2 = c^2 + d^2
$$
and such that $ac + bd$ is a divisor of $a^2 + b^2$.
MathNet 2023-part-06 — 191 problems (EN–VI) Question 54
Math Olympiad Vault · MathNet 2023-part-06 — 191 problems (EN–VI)