Advertisement Remove all ads

The curved surface area of one cone is twice that of the other while the slant height of the latter is twice that of the former. The ratio of their radii is - Mathematics

MCQ

The curved surface area of one cone is twice that of the other while the slant height of the latter is twice that of the former. The ratio of their radii is

Options

  •  2 : 1

  • 4 : 1

  • 8 : 1

  • 1 : 1

Advertisement Remove all ads

Solution

The formula of the curved surface area of a cone with base radius ‘r’ and slant height ‘l’ is given as

Curved Surface Area = `pirl`

Now there are two cones with base radius, slant height and Curved Surface Area (C.S.A) as `r_1`,`l_1`, `C.S.A_1` & `r_2`, `l_2`,`c,S,A_2` respectively.

It is given that `C.S.A_1`  = 2(`c,S,A_2` ) and also that `l_2` = 2(`l_1`). Or this can also be written as

`(l_2)/(l_1)=2`

`(C.S.A_1) / (C.S.A_2) = (pir_1l_1)/(pir^2l^2)`

`2(C.S.A_2) / (C.S.A_2) = (pir_1l_1)/(pir^2l^2)`

`r_1/r_2=(2l_2)/l_1`

`r_1/r_2=((2)(2))/1`

`r_1/r_2=4/1`

  Is there an error in this question or solution?
Advertisement Remove all ads

APPEARS IN

RD Sharma Mathematics for Class 9
Chapter 20 Surface Areas and Volume of A Right Circular Cone
Q 7 | Page 24
Advertisement Remove all ads

Video TutorialsVIEW ALL [1]

Advertisement Remove all ads
Share
Notifications

View all notifications


      Forgot password?
View in app×