Linked from

The 27 pages that link to Law of cosines, each with the reason it gives.

• Pythagorean theoremNarrower topic: Setting the included angle to 90 degrees reduces this broader triangle relation to the theorem.

• TriangleRelated: It generalizes the Pythagorean theorem to triangles that need not be right-angled.

• Solar irradianceRelated: It explains why a tilted surface receives less direct irradiance than a sun-facing one.

• Heron's formulaRelated: It links the three given sides to the angle used in a geometric derivation.

• Right triangleCompared with: It handles general triangles, while the Pythagorean theorem is its right-angle case.

• CosineRelated: It extends the Pythagorean theorem by using the cosine of a triangle angle.

• Ptolemy's theoremRelated: Applying it to triangles split by a diagonal gives an algebraic route to the identity.

• Law of sinesCompared with: It handles side-angle configurations where the law of sines does not directly determine the unknown.

• Parallelogram lawRelated: It gives a geometric route to the law through the angles between vector sums and differences.

• Spherical law of cosinesCompared with: Its flat-space formula is the limiting counterpart of the spherical law.

• Ptolemy's inequalityRelated: Applying it to triangles formed by a diagonal gives an algebraic route to the bound.

• Scalene triangleRelated: It finds unknown sides or angles in scalene triangles when right-angle methods do not apply.

• Pythagorean trigonometric identityCompared with: Unlike the Pythagorean identity, it relates three side lengths in a general triangle.

• Stewart's theoremRelated: Applying it to the two triangles formed by a cevian yields Stewart’s relation.

• Weitzenböck's inequalityRelated: Writing area with two sides and their included angle gives a direct route to the inequality.

• Euler's quadrilateral theoremRelated: Applying it to triangles formed by a diagonal can derive quadrilateral length identities.

• Hadwiger–Finsler inequalityRelated: Substituting its side-length identity exposes how angle geometry constrains the inequality.

• Pedoe's inequalityRelated: It links side-length data to angles used in equivalent proofs.

• Apollonius's theoremRelated: Applying it to the two triangles formed by the median yields the theorem after combining the equations.

• Jamshid al-KashiRelated: Al-Kashi gave a general form of this relation that became known in Persian tradition by his name.

• De Gua's theoremCompared with: It handles non-right triangular geometry, whereas De Gua's theorem requires three perpendicular edges.

• Haruki's theoremRelated: It offers an algebraic method for comparing lengths when angles are known.

• Hinge theoremRelated: With two fixed sides, it directly relates the included angle to the opposite side.

• Inverse Pythagorean theoremRelated: Setting a² + b² = c² in this formula forces the opposite angle’s cosine to zero.

• Law of cotangentsCompared with: It constrains side lengths and angles rather than a sum of cotangent products.

• Mollweide's formulaRelated: It offers a separate way to verify or transform the side-angle relations.

• Steiner–Lehmus theoremRelated: It can connect the triangle’s angles and side lengths in algebraic proofs.