Question

If two cones have equal diameters and their slant heights are in the ratio 3 : 4, then ratio of their CSA is .

• A. 3 : 5
• B. 3 : 4
• C. 5 : 3

Answer 1

The correct option is B 3 : 4

Since diameters are equal, radii of cones are also equal i.e. $r_1=r_2=r$
Curved surface area of the first cone
$=\pi \times r\times l_1$
Curved surface area of the second cone
$=\pi \times r\times l_2$
Ratio of curved surface area = $\frac{CSAofcone1}{CSAofcone2}=\frac{\pi \times r\times l_1}{\pi \times r\times l_2}=\frac{l_1}{l_2}=\frac{3}{4}$