Question

answer this question pls
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Answer 1

${\pink{\underline{\rm{Given :-}}}}$

• Solid cylinder has total surface area of 48π cm²
• Surface area if 8/5 times of its curved surface area

${\red{\underline{\rm To\:Find:-}}}$

• Radius

${\green{\underline{\rm Solution:-}}}$

⇒ TSA = 8/5 × CSA

⇒ 48π = 8/5 × CSA

⇒ 48π × 5/8 = CSA

⇒ 30π = CSA

Now

We know that

⇒ TSA of cylinder = 2πr² + 2πrh

⇒ CSA of cylinder = 2πrh

So,

⇒ TSA = 2πr² + CSA

⇒ 48π = 2πr² + 30π

⇒ 48π - 30π = 2πr²

⇒ 18π = 2πr²

⇒ 18 = 2r²

⇒ 18/2 = r²

⇒ 9 = r²

⇒ 3 = r

${\underline{\pmb{\sf \therefore Radius\;of\;cylinder\;is\;3\;cm.}}}$