Question

1.Jari² = 28 cm
Diameter = .... cm
Luas = ... m²
Keliling = ... cm

2.Jari² = .. cm
Diameter = 70 cm
Luas = ... m²
Keliling = ... cm

Answer 1

1. diameter = 28 x 2 = 56 cm
    luas lingkaran = phi r^2 = 22/7 x 28^2 = 22 x 112 = 2464 cm^2 = 0,2464 m^2
    keliling lingkaran = 2 phi r = 2 x 22/7 x 28 = 2 x 22 x 4 = 176 cm

2. jari-jari = 70 : 2 = 35 cm
    luas = phi r^2 = 22/7 x 35^2 = 22 x 175 = 3850 cm^2 = 0,385 m^2
    keliling = 2 phi r = 2 x 22/7 x 35 = 2 x 22 x 5 = 220 cm

Answer 2

1. D = r x 2 = 28 x 2 = 56 cm

    L = п x r² =22/7 x 28² = 22/7 x 784 = 224 m²

    K = 2 п r = 2 x 22/7 x 28 = 176

2. r = D/2 = 70/2 = 35

    L = phi r² = 22/7 x 35² = 22/7 x 1225

       = 350 m²

    K = 2 п r = 2 x 22/7 x 35 = 220