Hitunglah keliling dan luas daerah yang diarsir!

1. cari luas 1/4 lingkaran yang r = 14 cm
[tex]luas \: = \frac{1}{4} \times \pi \times {r}^{2} \\ = \frac{1}{4} \times \frac{22}{7} \times 14 \times 14\\ = \frac{1}{2} \times \frac{11}{7} \times 14 \times 14 \\ = 11 \times 14 = 154 \: {cm}^{2} [/tex]
2. cari 3/4 luas lingkaran yang r = 7 cm
[tex]luas \: = \frac{3}{4} \times \frac{22}{7} \times 7 \times 7 \\ = \frac{3}{2} \times \frac{11}{7} \times 7 \times 7 = \frac{3}{2} \times 11 \times 7 \\ = \frac{231}{2} = 115.5 \: {cm}^{2} [/tex]
3. cari luas arsir
[tex]luas \: = 154 - 115.5 = 38.5 \: {cm}^{2} [/tex]
1. keliling 1/4 lingkaran yang r = 14 cm
[tex]k = 2 \times \frac{22}{7} \times 14 = 2 \times 22 \times 2 \\ = 88 \: cm[/tex]
2. cari keliling 3/4 lingkaran yang r = 7 cm
[tex]k = \frac{3}{4} \times 2 \times \frac{22}{7} \times 7 = \frac{3}{2} \times 22 \\ = 33 \: cm[/tex]
3. keliling arsiran
[tex]k = k1 + k2 + 7 + 7 \\ k = 88 + 33 + 14 \\ k = 135 \: cm[/tex]