Let r cm be the radius, h cm be the height of the cylinder then
r = 3.5 cm
and h = 20 cm.
Let r1 be the radius of the hemisphere, then
r1 = 3.5 cm
Now,
Total surface area of the area of the article
= curved surface area of the cylinder
+ 2 (curved surface area of hemisphere)
= 2πrh + 2 (2 πr12)
= 2 πrh + 4 πr2 [∵ r = r1]
= 2 π r(h + 2r)
The decorative block shown in fig. is made of two solids - a cube and a hemisphere. The base of the block is a cube with edge 5 cm, and the hemisphere fixed on the top has a diameter of 4.2 cm. Find the total surface area of the block.
(Use π = 3.14).