`math` is Go’s standard library package for basic mathematical constants and functions (mostly for `float64`).

• Common math functions: sqrt, pow, trig functions.
• Math constants like Pi and E.

r := 2.0
area := math.Pi * r * r      // circle area
root := math.Sqrt(9)         // 3

• `math.Pi`: value of Pi
• `math.E`: Euler’s number
• `math.Sqrt(x)`: square root
• `math.Pow(x, y)`: power
• `math.Sin/Cos/Tan`: trigonometry

• `math` works with floating-point numbers (`float64`).
• For random numbers, use `math/rand` (different package).

• constant /ˈkɑːnstənt/: hằng số
• square root /skwer ruːt/: căn bậc hai
• trigonometry /ˌtrɪɡəˈnɑːmətri/: lượng giác
• floating-point /ˈfloʊtɪŋ pɔɪnt/: số dấu phẩy động