Bagaimana Cara no 20 & 21

20. keliling 1/2 lingkaran
=1/2 2πr
=1/2 ×2×3,14×2,5
=7,85

a.7,85 cm

21.Luas permukaan balok ::
=2(pl+pt+lt)
=2(25×5+25×8+8×5)
=2(125+200+40)
=2(365)
=730

c.730cm^2

:))

20. K = 1/2 × pi × d = 1/2 × 314/100 × 5 = 7,85 cm

21. Lp Balok = 2 × (pl +pt +lt) = 2×(25×5 + 25×8 + 8×5) = 2×(125+200+40) = 2×365 = 730 cm2