Question Details

A conical structure and a hemispherical structure share the same base radius r. If the curved surface area of the cone is equal to the curved surface area of the hemisphere, express the slant height l of the cone in terms of r.

Options

A

l = 2r

B

l = 4r

C

l = r

D

l = 3r

Show Answer

Correct Answer :

Option A

l = 2r

l = 2r

Solution :

Correct Answer: l = 2r

Step-by-step explanation:

Let r be the common base radius of the conical structure and the hemispherical structure, and let l be the slant height of the cone.

The curved surface area (CSA) of a cone is calculated using the formula:

CSAcone=πrl

The curved surface area (CSA) of a hemisphere is calculated using the formula:

CSAhemisphere=2πr2

According to the problem statement, the curved surface area of the cone is equal to the curved surface area of the hemisphere:

CSAcone=CSAhemisphere

Substituting the respective formulas into the equation:

πrl=2πr2

To find the slant height l in terms of r, divide both sides of the equation by πr (since radius r > 0 and π ≠ 0):

l=2πr2πr

Simplifying the right-hand side:

l=2r

Therefore, the slant height l of the cone expressed in terms of r is l = 2r.

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