Similar to 角の二等分線の定理

Open mapping theorem (complex analysis)

Rank–nullity theorem

Gauss's lemma (number theory)

Carathéodory's theorem (convex hull)

Leibniz formula for determinants

Locally connected space

Coupon collector's problem

Kőnig's lemma

Tree of primitive Pythagorean triples

Cauchy's mean value theorem

Mean value theorem (divided differences)

Schiffler point

Shannon's source coding theorem

Noisy-channel coding theorem

Jordan's lemma

Sylvester–Gallai theorem

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

Ptolemy's theorem

Sz.-Nagy's dilation theorem

Seven circles theorem