A heap of wheat is in the form of a cone whose diameter is 10.5 m and height is 3 m. Find its volume. The heap is to be covered by canvas to protect it from rain. Find the area of the canvas required.
Solution:
Since the heap of wheat is in the form of a cone and the canvas required to cover the heap will be equal to the curved surface area of the cone.
Volume of a cone of base radius, 'r' and height, 'h' = 1/3πr²h
Curved surface area of the cone having a base radius, 'r' and slant height, 'l' = πrl
Slant height of the cone, l = √r² + h²
Diameter of the conical heap, d = 10.5 m
Radius of the conical heap, r = 10.5/2 m = 5.25 m
Height of the conical heap, h = 3 m
Volume of the conical heap = 1/3πr²h
= 1/3 × 22/7 × 5.25 m × 5.25 m × 3 m
= 86.625 m³
Slant height, l = √r² + h²
= √(5.25)² + (3)²
= √27.5625 + 9
= √36.5625
= 6.046 m (approx.)
The area of the canvas required to cover the heap of wheat = πrl
= 22/7 × 5.25 m × 6.046 m
= 99.759 m²
The volume of the conical heap is 86.625 m³ and the area of the canvas required is 99.759 m².
☛ Check: NCERT Solutions for Class 9 Maths Chapter 13
Video Solution:
A heap of wheat is in the form of a cone whose diameter is 10.5 m and height is 3 m. Find its volume. The heap is to be covered by canvas to protect it from rain. Find the area of the canvas required.
NCERT Solutions for Class 9 Maths Chapter 13 Exercise 13.7 Question 9
Summary:
It is given that the heap of wheat is in the form of a cone whose diameter is 10.5 m and height is 3 m. We have found that the volume of the conical heap is 86.625 m³ and the area of the canvas required is 99.759 m².
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