Tolong dibantu yanomor 19 sampai 21PAKAI CARA ya….

19.luas = π × r × r
= 3,14 × 40/2 × 40/2
= 3,14 × 20 × 20
= 3,14 × 400
= 1.256 cm²
= 1.256 ÷ 4
= 314 cm²

20.luas = π × r × r
3,14 × 40/2 × 40/2
= 3,14 × 20 × 20
= 3,14 × 400
= 1.256 cm² ÷ 2
= 628 cm²
21.gk bisa , lupa pelajaran kelas 6

maaf jika salah , semoga membantu