JAWABAN BESERTA CARA

NO 1:

Diketahui:

jari-jari atau r = 14 cm

π = 22/7 (karena r dapat dibagi 7)

Keliling:

2×π×r

= 2×22/7×14

= (14:7)×2×22

= 2×2×22

= 2×44

= 88 cm

Luas:

π×r×r

= 22/7×14×14

= (14:7)×22×14

= 2×22×14

= 44×14

= 616 cm²

NO 2:

Diketahui:

Diameter atau d = 21 cm

π = 22/7 (karena 21 bisa dibagi 7)

Keliling:

π×d (dalam rumus ini, 2 tidak dipakai seperti di nomor 1 karena d adalah r×2)

= 22/7×21

= (21:7)×22

= 3×22

= 66 cm

Luas:

π×r×r

= d = 21:2 = 10,5 maka π yang dipakai adalah 3,14.

= 3,14×10,5×10,5

= 3,14×110,25

= 346,185 cm²

NO 3:

Diketahui:

D = 28 cm

π = 22/7

Keliling:

π×d

= 22/7×28

= (28:7)×22

= 4×22

= 88 cm

Luas:

π×r×r

= r = 28:2= 14 maka π adalah 22/7

= 22/7×14×14

= (14:7)×22×14

= 2×22×14

= 44×14

= 616 cm²

NO 4:

Diketahui:

r = 35 cm

π = 22/7

Keliling:

2×π×r

= 2×22/7×35

= (35:7)×22×2

= 5×22×2

= 220 cm

Luas:

π×r×r

= 22/7×35×35

= (35:7)×22×35

= 5×22×35

= 3.850 cm²

NO 5:

Diketahui:

D = 42 cm

r = 42:2=21

π = 22/7

Keliling:

π×d

= 22/7×42

= (42:7)×22

= 6×22

= 132 cm

Luas:

π×r×r

= 22/7×21×21

= (21:7)×22×21

= 3×22×21

= 66×21

= 1.386 cm²

NO 6:

Diketahui:

D = 40 cm

r = 20 cm

π = 3,14

Keliling:

π×d

= 3,14×40

= 125,6 cm

Luas:

π×r×r

= 3,14×20×20

= 3,14×400

= 1.256 cm²

NO 7:

Diketahui:

r = 16 cm

π = 3,14

Keliling:

2×π×r

= 2×3,14×16

= 6,28×16

= 100,48 cm

Luas:

π×r×r

= 3,14×16×16

= 803,84 cm²

NO 8:

Diketahui:

D = 50

r = 25

π = 3,14

Keliling:

π×d

= 3,14×50

= 157 cm

Luas:

π×r×r

= 3,14×25×25

= 3,14×625

= 1.926,5 cm²

NO 9:

Diketahui:

D= 7 cm

r = 3,5

π = 22/7

Keliling:

π×d

= 22/7×7

= (7:7)×22

= 1×22

= 22 cm

Luas:

π×r×r

= 22/7×3,5×3,5 cm²

= (3,5:7)×22×3,5

= 0,5×22×3,5

= 38,5 cm²

NO 10:

Diketahui:

r = 10

π = 3,14

Keliling:

2×π×r

= 2×3,14×10

= 2×31,4

= 62,8 cm

Luas:

π×r×r

= 3,14×10×10

= 314 cm²

Semoga membantu! Tulis di kolom komentar jika ada kesalahan atau pertanyaan, ya!