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If R is the radius of the base of the hat, then the total outer surface area of the hat is ______. - Mathematics

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Question

If R is the radius of the base of the hat, then the total outer surface area of the hat is ______.

Options

  • πr(2h + R)

  • 2πr(h + R)

  • 2πrh + πR2 

  • None of these

MCQ
Fill in the Blanks

Solution

If R is the radius of the base of the hat, then the total outer surface area of the hat is 2πrh + πR2.

Explanation:

Given, a cylindrical hat with base radius R and r is the radius of the top surface.

Now, total surface area of hat = Curved surface area + Top surface area + Base surface area

= 2πrh + πr2 + π(R2 – r2)

= 2πrh + πr2 + πR2 – πr2

= 2πrh + πR2 

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Chapter 11: Mensuration - Exercise [Page 349]

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NCERT Exemplar Mathematics [English] Class 8
Chapter 11 Mensuration
Exercise | Q 28. | Page 349

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