diketahu kelilingnya 66 cm tentukan luasnya diameter dan jari jarinya

K= 2\pi r[/tex]
66 = 2×22/7×r
66= 44/7 r
r= 21/3 cm
diameter = 2×r= 2×22/3 = 44/3 cm
L= phi r²
= 22/7×(21/3)²
=22/7 ×441/9 = 1386 / 9=154 cm² 

Keliling = 2 x π x r
Atau...
Keliling = π x D

66 cm =  3,14 x D
D = 66 / 3,14
Diameter = 21,01 cm

r = D / 2
= 21,01 / 2
Jari jari = 10,5

Luas = π x r²
= [tex] \frac{22}{7} [/tex] x 10,5 x 10,5
Luas = 346,5 cm²