Saved Bookmarks
| 1. |
The area of the circular base of a cone is 616 cm2 and its height is 48 cm. Find its whole surface area. [take π = 22/7 ] |
|
Answer» We have height of circular cone is h = 48 cm. And the area of the circular base of the cone is 616 cm2. Let the radius of base of circular cone is r cm. ∴ πr2 = 616 ⇒ r2 = \(\frac{616}{\pi}\) = \(\frac{616}{22}\) × 7 = 28 × 7 = 72 × 22 ⇒ r = 7 × 2 = 14 cm. ∴ Radius of the base of cone is r = 14 cm. The slant height of the cone is l = \(\sqrt{r^2+h^2}\) = \(\sqrt{14^2+48^2}\) = \(\sqrt{196+2304}\) = \(\sqrt{2500}\) = 50cm. Now, The whole surface area of cone = πr(r + l) = \(\frac{22}{7}\) × 14(14 + 50) = 22 × 2 × 64 = 2816 cm2. ∴ The whole surface area of the cone is 2816 cm2. |
|