Linked from

The 21 pages that link to Pi, each with the reason it gives.

• CircleRelated: This constant links every circle’s circumference to its diameter.

• ArchimedesRelated: His bounds for this ratio were exceptionally precise for antiquity.

• Irrational numberBroader topic: Its irrationality was proved in the eighteenth century.

• Transcendental numberBroader topic: Its transcendence was proved by Ferdinand von Lindemann in 1882.

• RadiusRelated: It gives the circumference formula in terms of radius: 2πr.

• DiameterRelated: Multiplying the diameter by π gives the circle’s circumference.

• Joseph LiouvilleRelated: The transcendence of pi became a landmark application of later methods in the tradition Liouville helped initiate.

• Euler's identityRelated: The angle π radians represents half a turn in the unit circle interpretation.

• Euler's NumberRelated: Euler's formula links this geometric constant to e through complex exponentiation.

• Squaring the circleRelated: The problem helped make the exact nature of this constant central to its resolution.

• Johann Heinrich LambertRelated: Its irrationality was the subject of Lambert’s landmark 1761 proof.

• Liu HuiBroader topic: Liu Hui estimated this constant by comparing circles with inscribed polygons.

• Transcendence theoryBroader topic: Lindemann proved its transcendence, resolving the classical impossibility of squaring the circle.

• Constant (mathematics)Broader topic: It is a geometric constant that appears in formulas for circles and periodic phenomena.

• Madhava of SangamagramaRelated: Madhava’s series enabled unusually precise approximations of this constant.

• Basel problemRelated: The series' exact sum links an arithmetic sequence to this geometric constant.

• John WallisRelated: The Wallis product gives an infinite-product representation of π.

• Zu ChongzhiRelated: Zu Chongzhi’s best-known numerical result was an unusually precise bound on this constant.

• Jamshid al-KashiRelated: Al-Kashi computed a highly accurate value of pi using polygonal approximations.

• Mathematical constantBroader topic: Pi is a universal geometric constant that also appears throughout analysis.

• Proof that π is irrationalNarrower topic: The proof establishes a number-theoretic property of this geometric constant.