1. p adalah titik pusat lingkaran dengan keliling 88 cm. luas daerah yang diarsir adalah... a. 77 cm2 b. 308 cm2 c. 414 cm2 d. 616 cm2 2. keliling daerah yang d

1)
K = 88 cm
K = 2 × phi × r
88 = 2 × 22/7 × r
88 = 44/7 × r
r = 88 × 7/44
r = 14 cm
L daerah yang diarsir = 45°/360° × phi × r^2
= 1/8 × 22/7 × 14 × 14
= 77 cm^2 (a)
2)
r1 = 14 cm
r2 = 1/2×r1 = 1/2×14 = 7 cm

K daerah yang diarsir = K1 + K2 + K3

= (1/2×2×phi×r1) + (1/2×2×phi×r2) + (1/2×2×phi×r2)

= (1/2×2×22/7×14) + (1/2×2×22/7×7) + (1/2×2×22/7×7)

= 44 + 22 + 22
= 88 cm (b)

3)
r = 14 cm
sudut juring = 72°
L juring = 72°/360° × L lingkaran
L juring = 1/5 × phi × r^2
L juring = 1/5 × 22/7 × 14 × 14
L juring = 123,2 cm^2 (c)