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WEEK 6
TOPIC: MENSURATION
CONTENTS:
(g) Surface areas and volume of frustum of a cone and pyramid.
(h) Surface area and volume of compound shapes.
- Surface area of frustum of a cone and pyramids
- Volume of frustum of a cone and pyramid
- Surface area and volume of compound shapes.
TOTAL SURFACE AREA OF FRUSTUM OF CONE AND PYRAMIDS
A frustum is the remaining part of cone or pyramid when the top part is cut off as shown below. Daily examples of frustums are buckets, lamps shades e.t.c
For Surface area of the frustrum of a pyramid, we sum up all areas of the faces that make up the frustum.
For Surface area of the frustum of a cone,
Total surface area of a Closed frustum = π(height x sum of radii) + area of top and base circles.
Total surface area of a Open frustum (bucket) = π(height x sum of radii) + area of circle.
Example 1:
Find the total surface area of a bucket 36cm in diameter at the top and 24cm at the bottom.
The depth of the bucket is 30cm.
Solution
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