Tomhas-lìonaidh cruinne

Gus tomhas-lìonaidh cruinne obrachadh a-mach, cleachd am foirmle:

\(V = \frac{4}{3}\pi {r^3}\) far an e \(r\) an radius.

Diagram of a sphere with radius labelled as 'r'

Eisimpleir

Obraich a-mach tomhas-lìonaidh cruinne le radius 6 cm.

\[V = \frac{4}{3}\pi {r^3}\]

\[= \frac{4}{3} \times \pi \times {6^3}\]

Gabhaidh seo dèanamh air àireamhair le \(4 \div 3 \times \pi \times {6^3}\), a' cleachdadh \(\pi\) no, mura bheil àireamhair saidheansail agad, cleachd 3.14)

\[= 904.7786...\]

\[= 904.78\,c{m^3}\,(gu\,2\,id)\]

Question

Obraich a-mach tomhas-lìonaidh cruinne le radius 1.7 cm gu 1 ionad deicheach.

\[v=\frac{4}{3}\pi r^{3}\]

\[=\frac{4}{3}\times \pi \times 1.7^{3}\]

\[=21.7\,cm^{3}\]