Sebuah tabung berdiameter 14 cm dan tinggi 34 cm. Luas permukaan tabung tersebut adalah.... \((\pi = \frac{22}{7})\)

diketahui

\(\begin{aligned} d &= 14\ cm \\ t &= 34\ cm \\ \pi &= \frac{22}{7} \end{aligned}\)

ditanya

luas permukaan?

penyelesaian

luas alas dan atap

\(\begin{aligned} L_{alas} &= \frac{1}{4} \pi d^2 \\ &= \frac{1}{4}\times \frac{22}{7}\times 14^2 \\ &= \frac{\cancel{22}^{11}\times 14\times \cancel{14}^{\cancel{2}}}{\cancel{4}^{\cancel{2}}\times \cancel{7}} \\ &= 11\times 14 = 154\ cm^2 \end{aligned}\)

luas selimut

\(\begin{aligned} L_{selimut} &= K_{alas}\times t \\ &= \pi\times d\times t \\ &= \frac{22}{\cancel{7}}\times \cancel{14}^2\times 34 \\ &= 22\times 2\times 34 \\ &= 1496\ cm^2 \end{aligned}\)

luas permukaan tabung

\(\begin{aligned} L_{permukaan} &= L_{alas}+L_{atap}+L_{selimut} \\ &= 154+154+1496 \\ &= 1804\ cm^2 \end{aligned}\)