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.  

Answer 1

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`