Mathematics Form 2 Circle -2

1. Calculate the radius and the area of a circle with circumference 24.43 cm. Use π = 3.142

4.44cm, 51,5 cm²

3.89cm, 47.54cm²

3.89cm, 60 cm²

4.44cm, 57.65 cm²

r=C/2π
=24.43/2*π ≈ 3.89

A=πr2=π*3.89 ≈ 47.53889

Explanation

r=C/2π
=24.43/2*π ≈ 3.89

A=πr2=π*3.89 ≈ 47.53889

2. Calculate the radius and the circumference of a circle with area 3160 cm². Use π = 3.142

31.72cm, 178.5cm

31.72cm, 199.3cm

40.65cm,199.3cm

50.90cm, 144.4cm

r=Squareroot(A /π)
π=3160 π≈31.71528
C=2πr=2*π*31.72 ≈ 199.30264

Explanation

r=Squareroot(A /π)
π=3160 π≈31.71528
C=2πr=2*π*31.72 ≈ 199.30264

3. We use the formulae πr² to calculate circumference of a circle.

True

False

πr² for area of circle.

Explanation

πr² for area of circle.

4. Figure shows a pizza with diameter 20cm. The pizza is cut into 8 equal pieces. Find the length of arc for each pieces. Use π = 3.142

8.56 cm

10.11cm

14.3 cm

7.855 cm

45 /360 * 2 (3.142) (20/2) = 7.855cm

Explanation

45 /360 * 2 (3.142) (20/2) = 7.855cm

5. Figure shows distance from P to Q is 12cm. the radius is 40cm. Find ° x. Use π = 3.142

20°

17.19°

32.42°

23°

angle / 360 * 2 (3.142)(40) = 12
angle = 17.19 °

Explanation

angle / 360 * 2 (3.142)(40) = 12
angle = 17.19 °

6. Calculate the radius and the diameter of a circle with area 202.25 cm ². Use π = 3.142
Match the correct answers.

11cm, 22cm

9.36cm, 19.25cm

8.02cm, 16.4cm

13.4cm, 26.8cm

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 area is given as 202.25 cm^2. By rearranging the formula, we can solve for the radius.

202.25 = 3.142 * r^2

Dividing both sides by 3.142, we get:

r^2 = 64.5

Taking the square root of both sides, we find:

r = 8.02 cm

The diameter of a circle is twice the radius, so:

d = 2 * r = 2 * 8.02 = 16.04 cm

Therefore, the correct answer is 8.02 cm for the radius and 16.04 cm for the diameter.

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 area is given as 202.25 cm^2. By rearranging the formula, we can solve for the radius.

202.25 = 3.142 * r^2

Dividing both sides by 3.142, we get:

r^2 = 64.5

Taking the square root of both sides, we find:

r = 8.02 cm

The diameter of a circle is twice the radius, so:

d = 2 * r = 2 * 8.02 = 16.04 cm

Therefore, the correct answer is 8.02 cm for the radius and 16.04 cm for the diameter.

7. X is straight line segment that passes through the center of the circle and whose endpoints lie on the circle. X is

A diameter is a straight line segment that passes through the center of a circle and whose endpoints lie on the circle. In this case, X is described as a straight line segment that passes through the center of the circle and has its endpoints on the circle. Therefore, X is a diameter of the circle.

Explanation

A diameter is a straight line segment that passes through the center of a circle and whose endpoints lie on the circle. In this case, X is described as a straight line segment that passes through the center of the circle and has its endpoints on the circle. Therefore, X is a diameter of the circle.

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9. The area of colored sector is 1732.5 cm ². Find circumference of the circle. Use π = 22/7

31.5 cm

96 cm

124.64 cm

89.5 cm

angle of centre = 360 - 160 = 200
angle of centre / 360 = area of sector /area of circle

Explanation

angle of centre = 360 - 160 = 200
angle of centre / 360 = area of sector /area of circle

10. From the answer below, which is TRUE about sector.

The part of a circle enclosed by two radii of a circle and their intercepted arc.

A portion of the circumference of a circle.

The distance across a circle through its center.

A straight line segment whose endpoints both lie on the circle

This answer is not true about a sector. A sector is actually the part of a circle enclosed by two radii of a circle and their intercepted arc.

Explanation

This answer is not true about a sector. A sector is actually the part of a circle enclosed by two radii of a circle and their intercepted arc.