Lagrange's identity (disambiguation)

Lagrange's identity may refer to:
Lagrange's identity, an algebraic identity
Lagrange's identity (boundary value problem), an identity in calculus
Lagrange's trigonometric identities, two trigonometric identities
Lagrange's four-square theorem, a theorem from number theory
Lagrange polynomial for theorems relating to numerical interpolation
Euler–Lagrange equation of variational mechanics