Advertisements
Advertisements
प्रश्न
Find the radius of a sphere whose surface area is equal to the area of the circle of diameter 2.8 cm
Advertisements
उत्तर
Diameter of circle = 2.8 cm ⇒ radius = r = 1.4 cm
Area of a circle = `pir^2`
= `pi(1.4)^2`
= `1.96pi`
Surface area of sphere = `4pir^2`
Given ,
Surface area of sphere = Area of the circle
⇒ `4pir^2 = 1.96pi`
⇒ `r^2 = 1.96/4`
⇒ `r^2 = 0.49`
⇒ `r = 0.7 "cm"`
Radius of the sphere = 0. 7 cm
संबंधित प्रश्न
Find the surface area of a sphere of radius 10.5 cm.
`["Assume "pi=22/7]`
Find the surface area of a sphere of radius 5.6 cm.
`["Assume "pi=22/7]`
A right circular cylinder just encloses a sphere of radius r (see figure). Find
- surface area of the sphere,
- curved surface area of the cylinder,
- ratio of the areas obtained in (i) and (ii).
What is the least number of solid metallic spheres, each of 6 cm diameter, that should be melted and recast to form a solid metal cone whose height is 45 cm and diameter 12 cm?
The hollow sphere, in which the circus motor cyclist performs his stunts, has a diameter of 7 m. Find the area available to the motorcyclist for riding.
If the ratio of volumes of two spheres is 1 : 8, then the ratio of their surface areas is
A sphere is placed inside a right circular cylinder so as to touch the top, base and lateral surface of the cylinder. If the radius of the sphere is r, then the volume of the cylinder is
The radius of a sphere is 9 cm. It is melted and drawn into a wire of diameter 2 mm. Find the length of the wire in metre.
A certain number of metallic cones, each of radius 2 cm and height 3 cm are melted and recast into a solid sphere of radius 6 cm. Find the number of cones used.
The volume of a sphere is 905 1/7 cm3, find its diameter.
