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Solution for There Are Two Cones. the Curved Surface Area of One is Twice that of the Other. the Slant Height of the Later is Twice that of the Former. Find the Ratio of Their Radii. - CBSE Class 9 - Mathematics

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Question

There are two cones. The curved surface area of one is twice that of the other. The slant height of the later is twice that of the former. Find the ratio of their radii.  

Solution

Let curved surface area off 1^st cone = 2x 

CSA of 2^nd cone=x 

`"and slant height of 1 ^st cone=h "`

`"and slant height of 2 ^nd cone = 2h"` 

`"CSA of 1^st cone" / "CSA of 2^nd cone"=(2x)/x=2/1` 

⇒ `(pir_1l_1)/(pir_2l_2)=2/1` 

⇒ `r_1h/r_2h=2/1⇒r_1/r_2=4/1` 

 

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APPEARS IN

 R.D. Sharma Mathematics for Class 9 by R D Sharma (2018-19 Session) (with solutions)
Chapter 18: Surface Areas and Volume of a Cuboid and Cube
Q: 13
Solution for question: There Are Two Cones. the Curved Surface Area of One is Twice that of the Other. the Slant Height of the Later is Twice that of the Former. Find the Ratio of Their Radii. concept: Surface Area of a Right Circular Cone. For the course CBSE
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