Advertisements
Advertisements
Question
The circumference of a circle is numerically equal to its area. Find the area and circumference of the circle.
Advertisements
Solution
Let the radius of a circle = r cm
⇒ Circumference of a circle = 2πr cm
Area of a circle = πr2
Now,
Circumference of a circle
= Area of a circle
⇒ 2πr = πr2
⇒ 2 = r
Thus, we have
Area of a circle
= πr2
= 3.14 x 2 x 2
= 12.56cm2
Circumference of a circle
= Area of a circle
= 12.56cm2.
APPEARS IN
RELATED QUESTIONS
An elastic belt is placed around the rim of a pulley of radius 5 cm. (Fig. 10) From one point C on the belt, the elastic belt is pulled directly away from the centre O of the pulley until it is at P, 10 cm from the point O. Find the length of the belt that is still in contact with the pulley. Also find the shaded area (use π = 3.14 and `sqrt3=1.73)`

The perimeter of a sector of a circle of radius 5.2 cm is 16.4 cm. Find the area of the sector.
The radii of two circles are 19 cm and 9 cm, Find the radius of the circle which has circumference equal to the sum of the circumferences of the two circles.
A 7 m road surrounds a circular garden whose area is 5544 m2. Find the area of the road and the cost of tarring it at the rate of Rs.150 per sq m.
A hollow metallic cylindrical tube has an internal radius of 3.5 cm and height 21 cm. The thickness of the metal tube is 0.5 cm. The tube is melted and cast into a right circular cone of height 7 cm. Find the radius of the cone, correct to one decimal place.
A circus tent is cylindrical to a height of 5 m and conical above it. If its diameter is 42 m and slant height of the cone is 53 m, calculate the total area of the canvas required.
Find the total surface area and volume of a hemisphere whose radius is 10 cm.
Find the area and perimeter of the circles with following: Radius = 2.8cm
The perimeter of a sector of radius 5.2 cm is 16.4 cm, the area of the sector is ____________.
