Lagrange's Four-Square Theorem
A theorem also known as Bachet's Conjecture which was stated but not proven by Diophantus. It states that everyPositive Integer can be written as the Sum of at most four Squares. Althoughthe theorem was proved by Fermat 
using infinite descent, the proof was suppressed. Euler was unableto prove the theorem. The first published proof was given by Lagrange in 1770 and made use of the EulerFour-Square Identity.
- Pear Curve
- Pearls of Sluze
- Pear-Shaped Curve
- Pearson-Cunningham Function
- Pearson Kurtosis
- Pearson Mode Skewness
- Pearson's Correlation
- Pearson's Function
- Pearson Skewness
- Pearson's Skewness Coefficients
- Pearson System
- Pearson Type III Distribution
- Peaucellier Cell
- Peaucellier Inversor
- Peaucellier's Linkage
- Pedal
- Pedal Circle
- Pedal Coordinates
- Pedal Curve
- Pedal Line
- Pedal Point
- Pedal Triangle
- Peg Knot
- Peg Solitaire
- Peg Top