import。math

The `math` module in Python provides various mathematical functions and constants. Some of the commonly used functions in the `math` module are:

- `math.sqrt(x)`: Returns the square root of x.
- `math.floor(x)`: Returns the largest integer less than or equal to x.
- `math.ceil(x)`: Returns the smallest integer greater than or equal to x.
- `math.pow(x, y)`: Returns x raised to the power y.
- `math.sin(x)`: Returns the sine of x in radians.
- `math.cos(x)`: Returns the cosine of x in radians.
- `math.tan(x)`: Returns the tangent of x in radians.
- `math.log(x, base)`: Returns the logarithm of x with base base.

Some of the commonly used constants in the `math` module are:

- `math.pi`: Returns the value of pi (3.141592653589793).
- `math.e`: Returns the value of e (2.718281828459045).

To use the `math` module in Python, you can import it using the `import` statement:

import math

After importing the `math` module, you can use its functions and constants by prefixing them with `math.`. For example:

import math

print(math.sqrt(16))  # Output: 4.0
print(math.floor(4.9))  # Output: 4
print(math.sin(math.pi/2))  # Output: 1.0