Suatu lingkaran memiliki luas 16π².Keliling lingkaran tersebut adalah‽‽‽‽‽

Suatu lingkaran memiliki luas 16π².Keliling lingkaran tersebut adalah‽‽‽‽‽

a.4π cm. c.16π cm
b.8π cm. d.32π cm

Jawaban yang benar adalah B. 8π cm

Luas lingkaran = πr²
Keliling lingkaran = 2πr
Dimana,
π = 22/7 atau π = 3,14
r = jari-jari lingkaran

Ingat!
a² = b —> a = ±√b

Pembahasan,

Asumsi luas lingkaran = 16π

Maka,
Luas = πr²
πr² = 16π
r² = 16π/π
r² = 16
r = ±√(16)
r = ± 4
Karena r merupakan panjang jari-jari, maka r bernilai positif, jadi:
r = 4

Sehingga,
Keliling lingkaran = 2πr
Keliling lingkaran = 2.π.4
Keliling lingkaran = 8π

Jadi, keliling lingkaran = 8π cm.
Oleh karena itu, jawabannya adalah B.

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