The ratio of the curved surface area of two cones is 1 : 4 and the ratio of slant height of the two cones is 2 : 1. What is the ratio of the radius of the two cones? |
1 : 8 1 : 6 1 : 9 1 : 7 |
1 : 8 |
C.S.A of a cone =\(\pi \)rl ATQ, ratio of C.S.A of two cones: ⇒ \(\frac{\pi r_1 l_1}{\pi r_2 l_2}\) = \(\frac{1}{4}\) ⇒ \(\frac{r_1}{r_2}\) × \(\frac{2}{1}\) = \(\frac{1}{4}\) ⇒ \(\frac{r_1}{r_2}\) = \(\frac{1}{8}\) ⇒ r1 : r2 = 1 : 8 |