Minta bantuanya donggsekalian caranya ​

Jawaban:

12.keliling = 2×π×r

2×22/7

2×22×1= 88

12. keliling lingkaran

π 2r

22/7 x 2 x 14

88 cm (c)

13. diameter

keliling = π 2r

132 = π 2r

132/2 = π r

66 = π r

66/3.14 = r

21 = r

diameter = 2r

= 42 (d)

14. luas lingkaran

diameter = 2 x jari-jari

jari-jari = 15

π r²

3.14 x 15²

3.14 x 225

706.5 (a)

15. keliling

luas = π r²

38.5 = 22/7 x r²

12.25 = r²

r = 3.5

keliling = π 2 r

22/7 x 2 x 3.5

= 22 (b)