===== math package =====

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

==== What is it used for? ====
  * Common math functions: sqrt, pow, trig functions.
  * Math constants like Pi and E.

==== Examples ====
<code go>
r := 2.0
area := math.Pi * r * r      // circle area
root := math.Sqrt(9)         // 3
</code>

==== Common items ====
  * `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

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

==== Hard words (English) ====
  * **constant** /ˈkɑːnstənt/: hằng số
  * **square root** /skwer ruːt/: căn bậc hai
  * **trigonometry** /ˌtrɪɡəˈnɑːmətri/: lượng giác
  * **floating-point** /ˈfloʊtɪŋ pɔɪnt/: số dấu phẩy động