Question

find the surface area of sphere whose diameter is 21 CM​

Answer 1

Answer:

1386 cm²

Step-by-step explanation:

Radius (r) of sphere = 21/2 10.5 cm

Surface area of sphere = 4πr²

⇒ [4 X 22/7 X (10.5)²]

⇒1386cm²

Therefore, the surface area of a sphere having diameter 21 cm is 1386 cm².

Answer 2

The surface area of sphere is 1386 sq.cm.

Step-by-step explanation:

Diameter of sphere = 21 cm

Radius of sphere = $\frac{21}{2}=10.5 cm$

Surface area of sphere =$4 \pi r^2 = 4 \times \frac{22}{7} \times 10.5^2 =1386 cm^2$

Hence the surface area of sphere is 1386 sq.cm.

#Learn more:

The inner diameter of a circular well is 3.5m. It is 10m deep. Find: (a) its inner curved surface area (b) the cost of plastering its curved surface area at the rate of Rs 40 per sq m.

19. A conical tent is 10m high and radius of its base is 24m. Find: (a) Slant height of the tent. (b) Cost of the canvas required to make the tent, if the cost of 1 sq m canvas is Rs 70.

20.Find the radius of a sphere whose surface area is 154 sq cm.

21. A godown measure 40m x 25m x 15m. Find the maximum number of wooden crates each measuring 1.5m x 1.25m x 0.5m that can be stored in the godown.

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