all Python 3mathterm

math.pi

constants

The mathematical constant π ≈ 3.141592653589793. Used in trigonometry and geometry.

Syntax

math.pi

It is the nearest double to the true π, so math.sin(math.pi) returns about 1.2e-16 rather than zero — comparing such results to zero with == is pointless, use math.isclose with an abs_tol. Every trigonometric function in the module takes radians: convert degrees with math.radians(), otherwise you get a silently wrong answer and no error at all. For a full turn there is math.tau, which equals 2π.

Examples

import math
print(math.pi)  # → 3.141592653589793
print(2 * math.pi)  # → 6.283185307179586
print(math.pi ** 2)  # → 9.869604401089358
area = math.pi * 5**2
print(round(area, 2))  # → 78.54
print(math.tau / 2)  # → 3.141592...  (tau = 2*pi)
print(math.degrees(math.pi))  # → 180.0

See also

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