tolong bantu jawab ya kak,sama caranya juga... yg udah bantuin makasih... yg latihan 9 gak usah yaa...

1. Diameter = 14 x 2 = 28 cm    Luas = πr²             = 22/7 x 14²             = 22/7 x 196             = 22 x 28             = 616 cm²
2. Diameter = 21 x 2 = 42 cm    Luas = πr²             = 22/7 x 21²             = 22/7 x 441             = 22 x 63             = 1.386 cm²
3. Diameter = 10 x 2 = 20 cm    Luas = πr²            = 3,14 x 10²           = 3,14 x 100           = 314 cm²
4.Diameter = 15 x 2 = 30 cm   Luas = πr²           = 3,14 x 15²           = 3,14 x 225           = 96,5 cm²
5. Diameter = 12 x 2 = 24 cm    Luas = πr²             = 3,14 x 12²             = 3,14 x 144             =  452,16 cm²
semoga membantu :)