Geoimeatraidh
Cuimhnich:
\(\text{Radius} = \frac{1}{2}\,\text{trast-thomas}\)
\(\text{Trast-thomas} = 2\, × \text{radius}\)
Cearcall-thomhas
Airson cearcall sam bith le trast-thomhas, d, lorgaidh sinn an cearcall-thomhas, C, leis an fhoirmle:
\(C = \pi d\)
far a bheil \(\pi = 3.14\)
Question
Obraich a-mach cearcall-thomhas a' chearcaill gu h-ìosal.
\(C = \pi d\)
\(= 3.14 \times 20\)
\(= 62.8\,cm\)
Question
Obraich a-mach cearcall-thomhas a' chearcaill gu h-ìosal.
Mar a chì thu san diagram, 's e 12 cm an radius.
Cuimhnich:
\(\text{Trast-thomas} = 2 × \text{radius}\)
\(\text{Trast-thomas} = 2 × 12 = 24\,cm\)
\(C = \pi d\)
\(= 3.14 \times 24\)
\(= 75.36\,cm\)