Pythagorean Theorem

Lagrange's four-square theorem - Wikipedia

Table 1 from Extended Lagrange's four-square theorem

Lagrange's four-square theorem

Solved In Number Theory, Lagrange's four-square theorem

Lagrange's four-square theorem - Wikiwand

SOLVED: Theorem 8.35 (Lagrange's Four-Square Theorem) then n can be expressed as the sum If n is a number; of four squares: natural lattice A in 4-space is a set of the

Lagrange's four-square theorem

PDF) Quarternions and the Four Square Theorem

Why was this visual proof missed for 400 years? (Fermat's two square theorem)

Sum of squares, Part-2, Sum of four squares