RD Sharma - Mathematics

Book: RD Sharma - Mathematics

Chapter: 20. Surface Area and Volume of a Right Circular Cone

Subject: Mathematics - Class 9th

Q. No. 4 of Exercise 20.1

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The height of a cone is 21 cm. Find the area of the base if the slant height is 28 cm.


Height of cone (h) = 21 cm

Slant height ( l )=28 cm

l2=r2 + h2 =r == =7√7 cm

Area of the base = πr2=×cm2 = 1078 cm2

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