Jawaban:

1.a. 1.256cm²

b. 3.850cm²

2.a. r = 14cm , d = 28cm

b. r = 20cm , d = 40cm

c. r = 21cm , d = 42cm

d. r = 3cm, d = 6cm

3.a. 77cm²

b. 981,25cm²

c. 1.039,5cm²

Penjelasan dengan langkah-langkah:

1.a. r = 20cm

L = πr2

= 3,14 x 20 x 20

= 1.256cm²

b. r = 35cm

L = πr²

= 22/7 x 35 x 35

= 22 x 5 x 35

= 3.850cm²

2.a. L = 616cm² (π=22/7)

L = πr²

616 = 22/7 x r²

616 x 7/22 = r²

28 x 7 = r²

196 = r²

r = 14cm

d = 2 x 14 = 28cm

b. L = 1.256cm² (π=3,14)

L = πr²

1.256 = 3,14 x r²

1.256 = 314/100 x r²

1.256 x 100/314 = r²

4 x 100 = r²

400 = r²

r = 20cm

d = 2 x 20 = 40cm

c. L = 1.386cm² (π = 22/7)

L = πr²

1.386 = 22/7 x r²

1.386 x 7/22 = r²

63 x 7 = r²

441 = r²

r = 21cm

d = 2 x 21cm = 42cm

d. L = 2.826cm² (π=3,14)

L = πr²

2.826 = 3,14 x r²

2.826 = 314/100 x r²

2.826 x 100/314 = r²

9 = r²

r = 3cm

d = 2 x 3 = 6cm

3.a. r = 7cm

daerah yg di arsir 2 x 1/4 = 2/4 = 1/2

L = πr²

= 22/7 x 7 x 7

= 22 x 7

= 154cm²

Luas daerah lingkaran yang diarsir = 1/2 x 154

= 77cm²

b. d = 50cm

r = 1/2 x 50 = 25

daerah yang di arsir 1/2 lingkaran

L = πr²

= 3,14 x 25 x 25

= 1962,5cm²

Luas daerah yang diarsir = 981,25cm²

c. r = 21cm

daerah yang diarsir = 3/4 lingkaran

L = πr²

= 22/7 x 21 x 21

= 22 x 3 x 21

= 1.386cm²

Luas daerah yang diarsir = 3/4 x 1.386 = 1.039,5cm²