panjg busur

sudut AOB = 45°

jari” = 7cm

pjg busur = (sudut AOB/360°) × 2πr

= 45°/360° × 2.22/7.7

= 1/8 × 44 cm

= 44/8 cm

= 5,5 cm

luas juring

Sudut BOA = 72°

jari” = 20 cm

luas juring = (sudut BOA/360°) × πr²

= 72°/360° × 3,14.20.20 cm

= 1/5 × 1.256 cm²

= 251,2 cm² dibulatkan mnjdi 251 cm²