Question

The base circumferences of two cones are the same. If their slant heights are in the ratio 5 : 4, find the ratio of their curved surface areas. 

Answer 1

The base circumferences of the cones are equal, therefore the radius of base are equal. 

Let radius be r. 

Ratio between slant heights= 5:4 

Let slant height of first cone = 5x and of second cone = 4x 

Curved surface area of cone = `pirl`  (where l = slant height)

Ratio of curved surface areas = `(pir xx 5x)/(pir xx 4x)`

= `5/4`

Ratio of curved surface areas = 5:4