Similar to ケイシーの定理

Law of tangents

Analyticity of holomorphic functions

Linear independence

Diagonal lemma

Thales's theorem

Monotone convergence theorem

Intermediate value theorem

Taylor's theorem

Dirichlet integral

Thébault's theorem

De Moivre's formula

Ptolemy's theorem

Sz.-Nagy's dilation theorem

Napkin ring problem

Lazy caterer's sequence

Newton's theorem (quadrilateral)

Proof that e is irrational

Hardy–Littlewood inequality

Pappus's area theorem

Pappus's hexagon theorem

Banach–Alaoglu theorem

Banach fixed-point theorem

Tangent half-angle substitution

Pythagorean theorem

Lune of Hippocrates

Nyquist–Shannon sampling theorem

Fáry's theorem

Fatou's lemma