1. Circle
Radius, Diameter and Area
Presented By: Zeeshan Ali Mangi

3. Bicycle
Bike
Car
Bus
Aero plane
Swimming Pool
Circular Park

4. And so on like such examples in our daily life

5. Radius:
• Radius(r)= Diameter/2 or r=d/2
r
r r
• Any point from a circumference to the center of
circle is called Radius.
• It makes a small line segment.

6. Question
Q:1 if the diameter of a circle is 4cm then find its Radius?
r=d/2
r=4/2
r=2cm Ans:

7. Practice Questions
If the diameters of different circles are given below then find their
Radiuses?
Q: 10m
Q: 30cm
Q: 40km

8. r r
Diameter
• Diameter(d) = 2Radius or d= 2r
Diameter
• Any two points from a circumference to the
center of circle is called Diameter.
• It makes two small line segments.

9. Question
Q:1 if the radius of circle is 2cm then find its Diameter?
d=2r
d=2(2)
d=4cm Ans:

10. Practice Questions
• If the radiuses of different circles are given below then find their
diameters?
Q: 3m
Q: 4cm
Q: 6km

11. r
Circumference
• Circumference(C) = d∏ or 2∏r
Circumference or Perimeter or Circular boundary
d
Where d is diameter Where r is radius

12. Question
if the diameter of a circle is 7cm then find its circumference
C= 2∏r or d∏
C= d∏ where pie is approximately equal to ∏=22/7
C= 7(22/7)
C=22cm Ans:
Or r=d/2
r=7/2
C=2 ∏ r
C=2 ∏(7/2)
C= ∏ 7
C= (22/7)7 =22 Ans:

13. One interesting Fact about Circle

14. 8 parts
64 parts
32 parts
16 parts
Parallelogram

15. Area of Circle
• Circumference(C) = 2∏r
Half circumference = ½(2∏r) = ∏r
Width
Length
Circle

16. r
Half Circumference = ∏r
Radius = r
Area of a Circle = ∏r2

17. Q: If radius of a circle is 7cm then find its area?
Solution:
Area of a circle = ∏r2
= ∏(7)2
= ∏(49)
= (22/7)49
=22/7 Ans:

18. Q: If a person wants to travel 3km by a car, if the radius of a car’s tire is 5m then find
after how many rotations, it will cover that distance?
Solution:

19. Word Problem
r
7m (Width of the road)
• Find the area of the road and repairing it at the cost of 2m2/ ?
21m (radius of external
circular Walking track)