Similar to ケーニヒの補題

Banach fixed-point theorem

Tangent half-angle substitution

Pythagorean theorem

Lune of Hippocrates

Nyquist–Shannon sampling theorem

Fáry's theorem

Feuerbach's theorem

Petr–Douglas–Neumann theorem

Helly's theorem

Poincaré–Bendixson theorem

Power of a point

Menelaus's theorem

Monge's theorem

Jacobi's formula

Dominated convergence theorem

Laplace expansion

Law of cosines

Law of cotangents

Routh's theorem

Lexell's theorem

Taylor circle

L'Hôpital's rule

Rolle's theorem

Wiles's proof of Fermat's Last Theorem

Computability theory

Elementary recursive function

Analytical hierarchy

Slow-growing hierarchy