Advertisements
Advertisements
प्रश्न
The area of the base of a right circular cone is 154 cm2 and its height is 14 cm. Its curved surface area is
विकल्प
154`sqrt(5) "cm"^2`
`154 sqrt(7) "cm"^2`
`77sqrt(7) "cm"^2`
`77sqrt(5) "cm"^2`
उत्तर
`154 sqrt(5) "cm"^2`
Area of the base of the of a right circular cone = πr2
Therefore,
`=> 22/7xx"r"^2 = 154`
`=> "r"^2 = (154xx7/22)`
⇒ r2 = 49
⇒ r= 7 cm
Now, r = 7 cm and h = 14 cm
Then, slant height of the cone,`"l" = sqrt("r"^2 + "h"^2)`
`=sqrt((7)^2 + (14)^2)`
`=sqrt(49 + 196)`
`= sqrt(245)`
`= 7sqrt(5) "cm"`
Hence, the curved surface area of the cone = πrl
`= (22/7xx7xx7xxsqrt(5)) "cm"^2`
`=154 sqrt(5) "cm"^2`
APPEARS IN
संबंधित प्रश्न
In Fig. 5, a tent is in the shape of a cylinder surmounted by a conical top of same diameter. If the height and diameter of cylindrical part are 2.1 m and 3 m respectively and the slant height of conical part is 2.8 m, find the cost of canvas needed to make the tent if the canvas is available at the rate of Rs. 500/sq. metre `( "Use "pi=22/7)`
Find the ratio of the volumes of a cylinder and a cone having equal radius and equal height.
(A)1 : 2 (B) 2 : 1 (C) 1 : 3 (D) 3 : 1
A building is in the form of a cylinder surmounted by a hemi-spherical vaulted dome and contains \[41\frac{19}{21} m^3\] of air. If the internal diameter of dome is equal to its total height above the floor , find the height of the building ?
An iron pillar consists of a cylindrical portion 2.8 m high and 20 cm in diameter and a cone 42 cm high is surmounting it. Find the weight of the pillar, given that 1 cubic cm of iron weighs 7.5 gm.
The interior of a building is in the form of a cylinder of base radius 12 m and height 3.5 m, surmounted by a cone of equal base and slant height 12.5 m. Find the internal curved surface area and the capacity of the building.
The surface area of a sphere is 2464 cm2. If its radius be doubled, then what will be the surface area of the new sphere?
If the radii of the circular ends of a bucket 28 cm high, are 28 cm and 7 cm, then find its capacity and total surface area.
In a right circular cone, if the perpendicular height is 12 cm and the radius is 5 cm, then find its slant height.
The radii of the top and bottom of a bucket of slant height 45 cm are 28 cm and 7 cm, respectively. The curved surface area of the bucket is ______.
Ratio of area of a circle to the area of a square whose side equals radius of circle is 1 : π.
