Question

Find the radios of a hemisphere whose total surface area is 462cm?
(a) 5 cm
(b) 7 cm
(c) 10 cm
(d) 14 cm​

Answer 1

$Answer:-$

➝ Option .B) 7cm

$Explanation:-$

Given :-

• The total surface area of a hemisphere is 462cm.

To Find :-

• The Radius of a hemisphere.

Solution :-

Let r be radius of solid hemisphere.

We know, Total surface area of hemisphere is 3πr² ........(1)

The Total surface area of a hemisphere = 462cm² ......(2)

From 1 & 2,

➝ 3πr² = 462

➝  π × r² =  $\frac{462}{3}$

➝π × r² = 154

➝ r² = $\frac{154}{\pi }$

➝ r² = $\frac{154}{22/7}$

➝ r² = $\frac{154*7}{22}$

➝ r² = $\frac{1078}{22}$

➝ r² = 49

➝ r = √ 49

➝ r = 7cm

Hence, The Radius of a hemisphere is 7cm .

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