- TeoremasTangents and Radius TheoremAngle at the centre TheoremTwo Tangents TheoremTriangle Inequality TheoremTeorema de NapoleãoTriangle Midsegment TheoremThe Theorem of Pythagoras by shear mappingTriangle Exterior Angle TheoremTriangle Sum TheoremExterior Angle TheoremTheorem 01 - Vertically Opposite AnglesTheorem 02 - Isosceles TriangleTheorem 03 - Alternate Angles and Parallel LinesPick's FormulaTheorem 11Theorem 21Theorem 19Theorem 16Theorem 18Theorem 15Theorem 14Theorem 20Theorem 13Theorem 12Theorem 8Theorem 9Theorem 10Theorem 4Theorem 5Theorem 6Theorem 1Theorem 2Theorem 3Corollary 1 to Theorem 10Corollary 2 to Theorem 19Corollary 3 to Theorem 19Corollary 4 to Theorem 19Corollary 5 to Theorem 19Corollary 6 to Theorem 20Axiom 4 (2)Axiom 4 (4)Axiom 4 (1)Axiom 5Axiom 3Axiom 2Axiom 1