panjang jari jari lingkaran diketahui 20 cm hitunglah a. panjang busur di hadapan sudut 30° b.luas juring di hadapan sudut 45°

a. busur = 30/360 x 2 x 3,14 x 20
= 125,6/12
= 10,47 cm

b. luas juring = 45/360 x 3,14 x 20²
= 1.256/8
= 157 cm²

≡ penyelesaian :

a.) panjang busur jika 30° :

Pb = α° / 360° × 2πr
Pb = 30° / 360° × 2 × 3,14 × 20
Pb = 1 / 12 × 2 × 3,14 × 20
Pb = 1 / 12 × 125,6
Pb = 10,46 cm

b.) Luas juring jika 45° :

Lj = α° / 360° × πr²
Lj = 45° / 360° × 3,14 × 20 × 20
Lj = 1 / 8 × 1256
Lj = 157 cm²

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