Soal Latihan Matematika Kelas 8 Semester 2 : Bab Lingkaran

1.

Bagian yang diarsir pada gambar disebut ...

Juring

Tembereng

Tali Busur

Busur

The highlighted part in the image is called "Tembereng."

Explanation

The highlighted part in the image is called "Tembereng."

2. Roda sepeda adik mempunyai jari-jari yang panjangnya 20 cm, Dengan menggunakan nilai phi 3,14, luas roda tersebut adalah ...

12,56 cm^2

62,80 cm^2

1256 cm^2

6280 cm^2

The question asks for the area of the bicycle wheel. To calculate the area of a circle, we use the formula A = πr^2, where A is the area and r is the radius. In this case, the radius is given as 20 cm. Substituting the values into the formula, we get A = 3.14 * (20^2) = 3.14 * 400 = 1256 cm^2. Therefore, the correct answer is 1256 cm^2.

Explanation

The question asks for the area of the bicycle wheel. To calculate the area of a circle, we use the formula A = πr^2, where A is the area and r is the radius. In this case, the radius is given as 20 cm. Substituting the values into the formula, we get A = 3.14 * (20^2) = 3.14 * 400 = 1256 cm^2. Therefore, the correct answer is 1256 cm^2.

3. Luas lingkaran yang berdiameter 20 cm dan nilai phi = 3,14 adalah …

628

314

6,28

3,14

The formula to calculate the area of a circle is A = πr^2, where A is the area and r is the radius. In this case, the diameter of the circle is given as 20 cm, so the radius would be half of that, which is 10 cm. Plugging in the value of π as 3.14 and the radius as 10 cm into the formula, we get A = 3.14(10^2) = 3.14(100) = 314. Therefore, the correct answer is 314.

Explanation

The formula to calculate the area of a circle is A = πr^2, where A is the area and r is the radius. In this case, the diameter of the circle is given as 20 cm, so the radius would be half of that, which is 10 cm. Plugging in the value of π as 3.14 and the radius as 10 cm into the formula, we get A = 3.14(10^2) = 3.14(100) = 314. Therefore, the correct answer is 314.

4. Sebuah roda sepeda jari-jarinya 42 cm. Jika roda itu berputar satu kali putaran maka jarak pergeseran roda itu adalah ... (

= 22/7)

154

264

324

441

The circumference of a circle is calculated by multiplying the diameter by π (pi). In this case, the diameter of the bicycle wheel is given as 42 cm. So, the circumference of the wheel is 42 cm x π. The question asks for the distance traveled by the wheel in one complete rotation, which is equal to the circumference of the wheel. Therefore, the correct answer is 42 cm x π, which is approximately equal to 264 cm.

Explanation

The circumference of a circle is calculated by multiplying the diameter by π (pi). In this case, the diameter of the bicycle wheel is given as 42 cm. So, the circumference of the wheel is 42 cm x π. The question asks for the distance traveled by the wheel in one complete rotation, which is equal to the circumference of the wheel. Therefore, the correct answer is 42 cm x π, which is approximately equal to 264 cm.

5. Pada sebuah lingkaran terdapat dua buah juring, yaitu juring AOB dan juring BOC dengan sudut pusat masing-masing sudut AOB = 120

dan sudut BOC = 60

. Jika luas juring AOB adalah 50 cm

, maka luas juring BOC adalah ... cm

20

25

50

100

The question states that there are two sectors in a circle, AOB and BOC, with central angles of 120° and 60° respectively. It is also given that the area of sector AOB is 50 cm². The area of a sector is proportional to the central angle, so the ratio of the areas of AOB and BOC will be the same as the ratio of their central angles.

Since the central angle of BOC is half of AOB, the area of BOC will be half of the area of AOB. Therefore, the area of BOC is 25 cm².

Explanation

The question states that there are two sectors in a circle, AOB and BOC, with central angles of 120° and 60° respectively. It is also given that the area of sector AOB is 50 cm². The area of a sector is proportional to the central angle, so the ratio of the areas of AOB and BOC will be the same as the ratio of their central angles.

Since the central angle of BOC is half of AOB, the area of BOC will be half of the area of AOB. Therefore, the area of BOC is 25 cm².

6. Amir membuat sebuah lingkaran dari seutas tali yang panjangnya 88 cm. Jika menggunakan nilai phi 22/7 maka panjang jari-jari lingkaran yang dibuat Amir adalah ...

14 cm

16 cm

22 cm

28 cm

Amir membuat sebuah lingkaran dari seutas tali yang panjangnya 88 cm. Untuk mencari panjang jari-jari lingkaran, kita dapat menggunakan rumus C = 2πr, di mana C adalah panjang lingkaran dan r adalah jari-jari lingkaran. Dalam hal ini, C = 88 cm. Dengan menggunakan nilai phi 22/7, kita dapat menggantikan nilai π dalam rumus tersebut. Jadi, 88 = 2 * (22/7) * r. Dengan melakukan perhitungan, kita dapat mencari nilai r = 14 cm. Oleh karena itu, panjang jari-jari lingkaran yang dibuat Amir adalah 14 cm.

Explanation

Amir membuat sebuah lingkaran dari seutas tali yang panjangnya 88 cm. Untuk mencari panjang jari-jari lingkaran, kita dapat menggunakan rumus C = 2πr, di mana C adalah panjang lingkaran dan r adalah jari-jari lingkaran. Dalam hal ini, C = 88 cm. Dengan menggunakan nilai phi 22/7, kita dapat menggantikan nilai π dalam rumus tersebut. Jadi, 88 = 2 * (22/7) * r. Dengan melakukan perhitungan, kita dapat mencari nilai r = 14 cm. Oleh karena itu, panjang jari-jari lingkaran yang dibuat Amir adalah 14 cm.

7. Seorang siswa ditugaskan untuk membagi sebuah lingkaran menjadi 6 bagian yang sama besar, Jika jari-jari lingkaran adalah 21 cm, dan

maka luas masing-masing bagian adalah ...

231

326

431

1386

To find the area of each section, we can divide the circle into 6 equal parts. The formula to find the area of a sector is (θ/360) * π * r^2, where θ is the angle of the sector and r is the radius of the circle. In this case, since we are dividing the circle into 6 equal parts, the angle of each sector is 360/6 = 60 degrees. Plugging in the values, we get (60/360) * π * 21^2 = 231. Therefore, the area of each section is 231.

Explanation

To find the area of each section, we can divide the circle into 6 equal parts. The formula to find the area of a sector is (θ/360) * π * r^2, where θ is the angle of the sector and r is the radius of the circle. In this case, since we are dividing the circle into 6 equal parts, the angle of each sector is 360/6 = 60 degrees. Plugging in the values, we get (60/360) * π * 21^2 = 231. Therefore, the area of each section is 231.

8. Sebuah lingkaran mempunyai dua buah juring, masing-masing juring AOB dengan sudut pusat

mempunyai panjang busur AB = 32 cm dan juring BOC dengan sudut pusat

, jika nila phi 22/7, maka panjang busur BC adalah...

78 cm

100 cm

120 cm

616 cm

The length of arc AB is given as 32 cm. Since the angle at the center of arc AB is not given, we cannot determine the radius of the circle or the measure of angle AOB. Therefore, we cannot directly calculate the length of arc BC. Without more information, it is not possible to determine the correct answer.

Explanation

The length of arc AB is given as 32 cm. Since the angle at the center of arc AB is not given, we cannot determine the radius of the circle or the measure of angle AOB. Therefore, we cannot directly calculate the length of arc BC. Without more information, it is not possible to determine the correct answer.

9.

Gambar di atas adalah gambar seperempat lingkaran sebuah Pizza. Jika luas pizza pada gambar diatas adalah 38,5 cm^2 maka panjang jari-jari lingkaran pizza yang utuh adalah ...

22 cm

21 cm

14 cm

7 cm

The given image represents a quarter of a pizza, and the area of the pizza in the image is 38.5 cm^2. To find the radius of the whole pizza, we need to multiply the area of the quarter pizza by 4. Therefore, 38.5 cm^2 x 4 = 154 cm^2. The formula to calculate the area of a circle is A = πr^2, where A is the area and r is the radius. Rearranging the formula, we get r = √(A/π). Plugging in the values, we get r = √(154/π) ≈ 7 cm. Therefore, the correct answer is 7 cm.

Explanation

The given image represents a quarter of a pizza, and the area of the pizza in the image is 38.5 cm^2. To find the radius of the whole pizza, we need to multiply the area of the quarter pizza by 4. Therefore, 38.5 cm^2 x 4 = 154 cm^2. The formula to calculate the area of a circle is A = πr^2, where A is the area and r is the radius. Rearranging the formula, we get r = √(A/π). Plugging in the values, we get r = √(154/π) ≈ 7 cm. Therefore, the correct answer is 7 cm.

10.

Jika diketahui phi = 22/7 dan jari-jari lingkaran = 7 cm, maka luas daerah juring AOB adalah ...

77/4

11/4

154

154/7

The formula for the area of a sector is A = (θ/360) * π * r^2, where θ is the central angle in degrees and r is the radius of the circle. In this case, the central angle is 360 degrees (a full circle) and the radius is 7 cm. Plugging in these values, we get A = (360/360) * (22/7) * 7^2 = (1) * (22/7) * 49 = 22 * 7 = 154. Therefore, the correct answer is 154.

Explanation

The formula for the area of a sector is A = (θ/360) * π * r^2, where θ is the central angle in degrees and r is the radius of the circle. In this case, the central angle is 360 degrees (a full circle) and the radius is 7 cm. Plugging in these values, we get A = (360/360) * (22/7) * 7^2 = (1) * (22/7) * 49 = 22 * 7 = 154. Therefore, the correct answer is 154.

11. Perhatikan gambar! Luas daerah arsiran adalah ....

40,25 cm²

42,50 cm²

50,25 cm²

52,50 cm²

not-available-via-ai

Explanation

not-available-via-ai

12. Berkaitan dengan sudut pusat dan sudut keliling pada sebuah lingkaran, manakah diantara pernyataan berikut yang benar?

sudut pusat = 1/2 dari sudut keliling yang menghadapi busur sama

sudut keliling adalah sudut dalam lingkaran yang titik sudutnya di dalam lingkaran

Sudut keliling yang menghadapi diameter lingkaran merupakan sudut siku-siku

Sudut pusat adalah sudut dalam lingkaran yang titik sudutnya di dalam lingkaran

The statement "Sudut keliling yang menghadapi diameter lingkaran merupakan sudut siku-siku" is correct because in a circle, the angle formed by a diameter and any point on the circumference is always a right angle. This is a property of circles and can be proven using the theorem that the angle subtended by a diameter at any point on the circumference is always a right angle.

Explanation

The statement "Sudut keliling yang menghadapi diameter lingkaran merupakan sudut siku-siku" is correct because in a circle, the angle formed by a diameter and any point on the circumference is always a right angle. This is a property of circles and can be proven using the theorem that the angle subtended by a diameter at any point on the circumference is always a right angle.

13.

Luas daerah yang diarsir adalah ...

60,6

61,6

72

72,6

The correct answer is 61,6.

Explanation

The correct answer is 61,6.