5. Hitunglah keliling lingkaran jika diketahui jari-jari atau diameternya :

Bagian A

• K = 2 × π × r
• K = 2 × ²²/7 × 21 cm
• K = 2 × 22 × 3 cm
• K = 44 × 3 cm
• K = 132 cm

Bagian B

• K = π × d
• K = ²²/7 × 49 cm
• K = 22 × 7 cm
• K = 154 cm

Jawaban:

A. Jari-jari = 21 cm

• 2 × π × r
• 2 × 22/7 × 21 × 1 cm
• 2 × 66 × 1 cm
• 132 cm

B. Diameter = 49 cm

• π × d
• 22/7 × 49 × 1 cm
• 154 cm