Doira yuzi

Doiraning radiusi R berilgan. Doiraning yuzini toping. Hisoblashda π = 3.14 deb oling.

func yuzi(R int) float64 {
    // ...
}

Misollar

Input: R=5
Output: 78.5

Input: R=10
Output: 314.0

Input: R=3
Output: 28.26

Maslahatlar

1. π = 3.14.
2. Doira yuzi: S = π · R · R.