tolong dijawab ya, pakai cara smp.

Ka = 72/360 × 2 × π × r
= 1/5 × 2 × 22/7 × 14
= 1/5 × 44 × 2
= 88 × 1/5
= 17,6 cm
La = 72/360 × π ×r^2 = 1/5 × 22/7 × 14^2 = 123,2 cm^2 Kb = 1/2 × 2 × π × r
= 1/2 × 2 × 22/7 × 21
= 1/2 × 44 × 3
= 22 × 3
= 66 cm Lb = 1/2 × π × r^2 = 1/2 × 22/7 × 21^2 = 693 cm^2