English
If x, y, z form a Pythagorean triple, then swapping x and y yields a Pythagorean triple as well; x^2 + y^2 = z^2 iff y^2 + x^2 = z^2.
Русский
Если x, y, z образуют Пифагорову тройку, то交换 x и y также образуют тройку; x^2 + y^2 = z^2 ⇔ y^2 + x^2 = z^2.
LaTeX
$$$PythagoreanTriple(x,y,z) \iff PythagoreanTriple(y,x,z)$$$
Lean4
/-- Pythagorean triples are interchangeable, i.e `x * x + y * y = y * y + x * x = z * z`.
This comes from additive commutativity. -/
theorem pythagoreanTriple_comm {x y z : ℤ} : PythagoreanTriple x y z ↔ PythagoreanTriple y x z :=
by
delta PythagoreanTriple
rw [add_comm]