मराठी

The diameter of two cones are equal. If their slant heights are in the ratio 5 : 4, find the ratio of their curved surface areas. - Mathematics

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प्रश्न

The diameter of two cones are equal. If their slant heights are in the ratio 5 : 4, find the ratio of their curved surface areas. 

बेरीज

उत्तर १

Let radius of each cone = r

Ratio between their slant heights = 5 : 4

Let slant height of the first cone = 5x

And slant height of second cone = 4x

Therefore, curved surface area of the first cone = πrl = πr × (5x) = 5πrx 

Curved surface area of the second cone = πrl = πr × (4x) = 4πrx

Hence, ratio between them = 5πrx : 4πrx = 5 : 4

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उत्तर २

Let their slant height be 5x and 4x.

Given that diameter of two cones are equal

∴ R1 = R2 = R

S1 = πRl = πR(5x)

S2 = πRl = πR(4x)

`(S_1)/(S_2) = (πR (5x))/(πR (4x)) = 5/4`

`(S_1)/(S_2) = 5/4`

S1 : S2 = 5 : 4.

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पाठ 17: Mensuration - Exercise 1

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आईसीएसई Mathematics [English] Class 10
पाठ 17 Mensuration
Exercise 1 | Q 10
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Exercise 20 (B) | Q 6 | पृष्ठ ३०३

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