One of the important question for the board exam class 10 from
mensuration chapter.This question is from r d sharma class 10 maths.
chapter-16.2 question number-4 maths r d sharma,mensuration.
In this question we have to find the surface area of the toy,
givwn that a toy is in the form of a cone surmounted on a hemisphere.
The diameter of the base and the height of the cone are 6 cm and 4 cm, respectively.
Given that,
The height of the cone (h) = 4 cm
Diameter of the cone (d) = 6 cm
So, its radius (r) = 3
Let, ‘l’ be the slant height of cone.
Then, we know that
l2 = r2 + h2
l2 = 32 + 42 = 9 + 16 = 25
l = 5 cm
Hence, the slant height of the cone (l) = 5 cm
So, the curved surface area of the cone (S1) = πrl
S1 = π(3)(5)
S1 = 47.1 cm2
And, the curved surface area of the hemisphere (S2) = 2Ï€r2
S2 = 2Ï€(3)2
S2 = 56.23 cm2
So, the total surface area (S) = S1 + S2
S = 47.1 + 56.23
S = 103.62 cm2
Therefore, the curved surface area of the toy is 103.62 cm2