"Question 5 An ant is moving around a few food pieces of different shapes scattered on the floor. For which food − piece would the ant have to take a longer round? Remember, circumference of a circle can be obtained by using the expression c = 2πr, where r is the radius of the circle. And also use the pie square as 3.14 Class 8 Mensuration Page 171"
Answers
Answer:
Remember, circumference of a circle can be obtained by using the expression c=2πr, where r is the radius of the circle. Clearly, for food ′b′ the ant has to go more.
Answer:
Circumference of a circle is the perimeter of a circle.
In a circle the radius is half of the diameter.
The approximate value of π( Pi) is= 22/7
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Solution:
i)
Given:
Diameter = 2.8 cm
Radius= 2.8/2= 1.4 cm
Perimeter of the figure = Perimeter of Semicircular part + Diameter of the part
= πr + 2r
=(22/7) × (1.4) + 2.8
= 22× .2 + 2.8 = 4.4+ 2.8
=7.2 cm
ii)
Given :
Diameter = 2.8 cm
Radius= 2.8/2= 1.4 cm
Perimeter of the figure = Perimeter of Semi-circular part + 2Length + Breadth
= πr +L+ 2B
= 22/7× 1.4 + 2.8+ 2× 1.5
= 22×.2 + 2.8+ 3
=4.4 + 2.8+ 3
=10.2 cm
iii)
Given :
Diameter = 2.8 cm
Radius= 2.8/2= 1.4 cm
Slant height= 2 cm
Perimeter of the shape = Perimeter of Semi-circular part + 2(slant height)
= πr + 2 (slant height)
= 22/7× 1.4 +2+2
=4.4 + 4
=8.4 cm
Hence, the food shape in (b) requires the ant to cover the more distance.
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Hope this will help you...