Pi (Π, π)
Quick Info
- Pronunciation: pie
- English: p
- Common Use: Circle ratio (3.14159...)
Historical Background
Sixteenth letter of the Greek alphabet, derived from Phoenician letter "pe", meaning mouth. The symbol π was first used by William Jones in 1706 to represent the ratio of a circle's circumference to its diameter, and was later popularized by Leonhard Euler.
Scientific Applications
Mathematics
Circle ratio
Physics
Pi mesons
Statistics
Product notation
Wave Theory
Phase angles
Complex Analysis
Euler's identity
Symbol Codes
Unicode
Uppercase
- Code: U+03A0
- Hex: Π
- Decimal: Π
Lowercase
- Code: U+03C0
- Hex: π
- Decimal: π
HTML
Uppercase
Π
HTML entity for uppercase Pi
Lowercase
π
HTML entity for lowercase pi
LaTeX
Uppercase
\Pi
LaTeX command for uppercase Pi
Lowercase
\pi
LaTeX command for lowercase pi
Common Usage
Mathematics
Geometry
Circle and sphere calculations
Trigonometry
Angular measurements
Complex Analysis
Euler's identity
Physics
Wave Theory
Phase angles and periods
Particle Physics
Pi mesons (pions)
Quantum Mechanics
Wave functions
Engineering
Signal Processing
Frequency analysis
Control Systems
Transfer functions
Structural Design
Circular elements
Common Applications
Geometry
Circle area
Sphere volume
Circle circumference
Wave Physics
Sinusoidal wave
Photon energy
Wave function
Famous Pi Formulas
Series Representations
Leibniz formula
Basel problem
John Machin's formula
Important Relations
Euler's identity
Basel solution
Gamma function at 1/2
Special Applications
Particle Physics
Neutral pion decay
Charged pion decay
Pion mass
Complex Analysis
Cauchy integral
Weierstrass factorization
Partial fraction expansion
Mathematical Applications
Calculus
- • Integration formulas
- • Fourier series
- • Complex analysis
- • Differential equations
Number Theory
- • Prime number distribution
- • Gaussian integrals
- • Riemann zeta function
- • Diophantine equations
Applied Mathematics
- • Signal processing
- • Control theory
- • Probability distributions
- • Statistical mechanics
Historical Calculations of π
Ancient Methods
Modern Computations
How to Type Pi
Windows
Alt Code
- Hold Alt
- Type 960 for π
- Release Alt
Character Map
- Open Character Map
- Select Greek
- Find and copy Pi
Unicode
- Hold Alt + X
- Type 03C0
- Release Alt + X
macOS
Option Key
- Press Option + p for π
Character Viewer
- Press Control + Command + Space
- Select Greek
- Click Pi
Linux
Compose Key
- Press Compose + p + i for π
Unicode
- Press Ctrl + Shift + U
- Type 03C0
- Press Enter
Frequently Asked Questions
Why is π used for the circle ratio?
The symbol π was chosen by William Jones in 1706 as it is the first letter of the Greek word "περίμετρος" (perimetros), meaning "circumference". It was later popularized by Leonhard Euler and became the standard notation.
What is the difference between π and τ?
While π represents the ratio of a circle's circumference to its diameter (approximately 3.14159), τ (tau) equals 2π and represents the ratio of circumference to radius. Some mathematicians argue that τ is more natural for certain calculations.
How accurate do we know π?
As of 2024, π has been calculated to over 100 trillion digits. However, for most practical applications, using 15-20 decimal places is more than sufficient.
Why are particles called pi mesons?
Pi mesons (pions) were named using π because they were the first discovered members of the meson family of particles. The Greek letter was chosen to continue the tradition of using Greek letters in particle physics notation.
Writing Guidelines
Uppercase resembles a gate or doorway (Π), lowercase is a curved line with two legs (π). In handwriting, ensure the lowercase π is clearly distinguished from the Greek tau (τ) and omega (ω). The legs should be straight and parallel.