Ch. 906. Measuring Space: Perimeter and Area

Ch. 906. Measuring Space: Perimeter and Area

6.1 Perimeter of a Shape
Perimeter : The perimeter is the total length around the border of any shape. 
In other words the perimeter of the shape is the total distance travels around it. lt returns to its starting point. 

EXERCISE SET 6.1

22/7 for π. Unless stated otherwise, use the approximation

1. The perimeter of a circle is 44 cm. What is its radius?
2. Calculate, correct to 3 significant figures, the circumference of a circle with: 
(i) radius 7 cm 
(ii) radius 10 cm 
(iii) radius 12 cm.
3. Calculate the length of the arc of a circle if: (i) the radius is 3.5 cm and the angle at the centre is 60°, and 
(ii) the radius is 6.3 m and the angle at the centre is 120°.

4. Find the perimeter of a sector (i.e., the curved portion as well as the two straight portions) of a circle of radius 14 cm and sector angle 75°.




5. Find the perimeters of the following shapes (taking the arcs to be quarter or half or three-quarters of a circle, as appropriate) (Fig. 6.14i to 6.14ix):
6. If the diameter of a car tyre is 56 cm, then: (i) How far does the car need to travel for the tyre to complete one revolution? 
(ii) How many revolutions does the tyre make if the car travels 10 km?

7. Find the total perimeter of all the petals in each of the given flowers.
8. The ratio of the perimeters of two circles is 5:4. What is the ratio of their radii?

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