Question

1)diket:luas lingkaran=1.256 cm²
phi=3,14
ditanya:jari-jari lingkaran???

2)diket:keliling lingkaran=176 cm
ditanya:jari-jari lingkaran???

Answer 1

Nomor 1
L = πr²
1256 = 3,14.r²
r² = 1256 / 3,14
r² = 400
r  = √400
r  = 20

Nomor 2
K = πd
176 = 22/7 . d
d = 56
r  = 56/2
r  = 28 cm

Answer 2

1) L = πr²
1256 = 3.14 r²
r = √1256 / 3.14
r = √400
r = 20cm
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2) K = πd
176 = 3.14 d
d = 176 / 3.14
d = 56.05
--------------------------
r = d/2
r = 56.05/2
r = 28.025