Short Answer 
Pi (π) is an irrational number critical in geometry, notably for calculating the area (A = πr²) and circumference (C = 2πr) of circles. The symbol for pi was introduced by William Jones in 1706 and popularized by Leonhard Euler, ensuring its recognition in mathematics globally.
Step 1: Understanding Pi
The concept of pi (π) is crucial in mathematics, particularly in geometry. It is an irrational number, which means its decimal representation is infinite and non-repeating, starting with 3.14159. Historically, civilizations such as the Babylonians and Egyptians discovered pi, illustrating its long-standing significance in mathematical studies.
Step 2: The Mathematical Uses of Pi
Pi is essential for various mathematical calculations, primarily in determining the properties of circles. It is used to compute:
- Area (A) of a circle using the formula A = πr², where r is the radius.
- Circumference (C) of a circle through the formula C = 2πr.
These calculations are fundamental in both theoretical and applied mathematics, emphasizing pi’s importance in geometry.
Step 3: Historical Significance of the Pi Symbol
The symbol for pi (œÄ) has a rich history. It was first introduced by William Jones, a Welsh mathematician, in 1706. The symbol gained widespread popularity through the work of the Swiss mathematician Leonhard Euler in the 18th century. This transition solidified the symbol’s place in mathematical literature and education, making pi a recognizable constant across the world.