Menghitung luas lingkaran (25 POIN) nomor 1 & 2 saja

Rumus:

L = π × r²

Info: Jika nilai r = kelipatan 7, maka pakai π = 22/7. Tetapi jika r ≠ kelipatan 7, maka pakai π = 3,14.

1). a). L = π × r² = 22/7 × 14 × 14

= 22 × 2 × 14 = 616 cm²

b). L = 3,14 × 30 × 30 = 2.826 cm²

c). L = 3,14 × 40 × 40 = 5.024 cm²

d). L = 22/7 × 42 × 42 = 22 × 6 × 42

= 5.544 cm²

e). L = 3,14 × 100 × 100 = 31.400 cm²

2). a). r = d/2 = 20/2 = 10 cm

L = 3,14 × 10 × 10 = 314 cm²

b). r = 28/2 = 14 cm

L = 22/7 × 14 × 14 = 22 × 2 × 14 = 616 cm²

c). r = 30/2 = 15 cm

L = 3,14 × 15 × 15 = 706,5 cm²

d). r = 50/2 = 25 cm

L = 3,14 × 25 × 25 = 1.962,5 cm²

e). r = 140/2 = 70 cm

L = 22/7 × 70 × 70 = 22 × 10 × 70 = 15.400 cm²