Advertisements
Advertisements
Question
The height of a cone is 21 cm. Find the area of the base if the slant height is 28 cm.
Solution
Given that
Slant height ‘l’ = 28 m.
Height of cone (h) = 21cm
∴ Radius of cone (r)=`sqrt(28^2-21^2)` [by Pythagoras theorem]
= `7sqrt(7cm)`
∴ Area of base = `pir^2`
= `22/7xx(7sqrt7)^2`
= `22/7xx7xx7=1078 cm^2`
APPEARS IN
RELATED QUESTIONS
The curved surface area of a cone is 4070 cm2 and its diameter is 70 cm. What is its slant height? (Use it ЁЭЬЛ = 22/7).
The ratio of volumes of two cones is 4 : 5 and the ratio of the radii of their bases is 2:3. Find the ratio of their vertical heights.
The curved surface area of a cone is 12320 cm2. If the radius of its base is 56 cm, find its height.
The total surface area of a right circular cone of slant height 13 cm is 90π cm2.
Calculate:
- its radius in cm.
- its volume in cm3. [Take π = 3.14].
The horizontal cross-section of a water tank is in the shape of a rectangle with semi-circle at one end, as shown in the following figure. The water is 2.4 metres deep in the tank. Calculate the volume of water in the tank in gallons.
Curved surface area of a cone is 251.2 cm2 and radius of its base is 8 cm. Find its slant height and perpendicular height. (π = 3.14)
The curved surface area of a cone is 2200 sq.cm and its slant height is 50 cm. Find the total surface area of cone. `(π = 22/7)`
A buoy is made in the form of a hemisphere surmounted by a right circular cone whose circular base coincides with the plane surface of the hemisphere. The radius of the base of the cone is 3.5 m and its volume is two-third the volume of hemisphere. Calculate the height of the cone and the surface area of the buoy, correct to two decimal places.
The circumference of the base of a 10 m high conical tent is 44 metres. Calculate the length of canvas used in making the tent if the width of the canvas is 2m. (Take π = 22/7)
The curved surface area of a right circular cone of height 15 cm and base diameter 16 cm is
