Advertisements
Advertisements
प्रश्न
The slant height of the frustum of a cone is 4 cm and the perimeters (i.e. circumferences) of its circular ends are 18 cm and 6 cm. Find the curved surface area of the frustum.
उत्तर
Let R and r be the radii of the top and base of the frustum of the cone, respectively, and its slant height be l.
Then,
2πR = 18 ⇒ πR = 9 .....(i)
2πR = 6 ⇒ πr = 3 .....(ii)
Curved surface area of the frustum =πl (R + r)
= l × (πR + πr )
= 4 × (9 + 3) [Since l = 4 cm] (From (i) and (ii))
= 48 cm2
APPEARS IN
संबंधित प्रश्न
Two cylindrical vessels are filled with oil. Their radii are 15 cm, 12 cm and heights 20 cm, 16 cm respectively. Find the radius of a cylindrical vessel 21 cm in height, which will just contain the oil of the two given vessels.
Find the weight of a hollow sphere of metal having internal and external diameters as 20 cm and 22 cm, respectively if 1m3 of metal weighs 21g.
An iron pole consisting of a cylindrical portion 110 cm high and of base diameter 12 cm is surmounted by a cone 9 cm high. Find the mass of the pole, given that 1 cm3 of iron has 8 gram mass approximately. (Use : π = 355/115)
A sphere and a cube have equal surface areas. What is the ratio of the volume of the sphere to that of the cube?
A toy is in the form of a cone mounted on a hemisphere of common base radius 7 cm. The total height of the toy is 31 cm. Find the total surface area of the toy.
A right triangle whose sides are 15 cm and 20 cm (other than hypotenuse), is made to revolve about its hypotenuse. Find the volume and surface area of the double cone so formed. (Choose value of π as found appropriate)
The total surface area of a hemisphere of radius 7 cm is
Two cubes, each of volume 64 cm3, are joined end to end. Find the total surface area of the resulting cuboid.
Match the column:
| (1) surface area of cuboid | (A) πr2h |
| (2) surface area of closed right cylinder | (B) 2πr(h + r) |
| (3) Total surface area of right cone | (C) πrl + πr2 |
| (4) Total surface area of hemisphere | (D) 3πr3 |
| (E) 3πr2 | |
| (F) 2[lb + bh + lh] |
A sphere and a cube have equal surface areas. The ratio of the volume of the sphere to that of cube is ______.
