tolong kak jawabanya........

18.
Luas Semangka
= Luas Setengah Bola Padat
[tex] = 3 \times \pi \times {r}^{2} \\ = 3 \times \frac{22}{7} \times 7 \times 7 \\ = 3 \times 22 \times 7 \\ = 462 \: {cm}^{2} [/tex]
19.
[tex] \frac{v \: tabung}{v \: kerucut} \\ = \frac{\pi \times {r}^{2} \times t }{ \frac{1}{3} \times\pi \times {r}^{2} \times t } \\ = \frac{1}{ \frac{1}{3} } \\ = 1 \div \frac{1}{3} \\ = 3 \div 1[/tex]