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:

ans is( b) for this question

7 cm

Step-by-step explanation:

TSA of hemisphere =3pi(r)²

462= 3× 22/7 × r²

=(462×7)/(3×22)= r²

=49 = r²

=r= 7cm

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Answer 2

$\sf{\huge{\underline{\red{Answer :-}}}}$

➝ Option .B) 7cm

$\sf{\huge{\underline{\green{Explaination :-}}}}$

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 = $\cancel{\dfrac{462}{3}}$

➝ π × r² = 154

➝ r² = ${\dfrac{154}{\pi}}$

➝ r² = ${\dfrac{154 }{22/7}}$

➝ r² = ${\dfrac{154 {\times 7 }}{22}}$

➝ r² = $\cancel{\dfrac{1078 }{22}}$

➝ r² = 49

➝ r = √ 49

➝ r = 7cm

Hence, The Radius of a hemisphere is 7cm .

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