Luas lingkaran dengan keliling 88cm adalah

[tex]k = 2 \times \pi \times r \\ 88 = 2 \times \frac{22}{7} \times r \\ \\ 88 = \frac{44}{7} \times r \\ r = 88 \div \frac{44}{7} \\ r = 88 \times \frac{7}{44} \\ r = 14 \: cm \\ \\ luas \: = \pi \times r \times r \\ = \frac{22}{7} \times 14 \times 14 \\ = 616 \: cm ^{2} [/tex]

misal : jari jari = r
keliling = 88 cm
22/7 × 2r = 88 cm
2r =88 : 22/7
2r =88 × 7/22
2r =28
r =14 cm

luas = π × r²= 22/7 × 14² = 22/7 × 196 = 616 cm²


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