Advertisements
Advertisements
Question
If the radius of a circle is tripled, the area becomes ______.
Options
9 times
3 times
6 times
30 times
Advertisements
Solution
If the radius of a circle is tripled, the area becomes 9 times.
Explanation:
Let r be the radius of a circle.
∴ Area of circle = πr2
If radius is tripled, then new radius will be 3r.
∴ Area of new circle = π(3r)2 = 9π2 = 9 times of original
Hence, the area of a circle becomes 9 times to the original area.
APPEARS IN
RELATED QUESTIONS
A rectangular plot measure 125 m by 78 m. It has gravel path 3 m wide all around on the outside. Find the area of the path and the cost of gravelling it at` ₹ 75 per m^2`
Find the area enclosed between two concentric circles of radii 3.5 cm and 7 cm. A third concentric circle is drawn outside the 7 cm circle , such that the area enclosed between it and the 7 cm circle is same as that between the two inner circles . Find the radius of the third circle correct to one decimal place.
From a circular piece of cardboard of radius 3 cm two sectors of 900 have been cutoff . Find the perimeter of the remaining portion nearest hundredth centimeters ( `"Take" pi = 22/ 7`).
A chord PQ of length 12 cm subtends an angle of 120° at the centre of a circle. Find the area of the minor segment cut off by the chord PQ.
In the following figure, AB and CD are two diameters of a circle perpendicular to each other and OD is the diameter of the smaller circle. If OA = 7 cm, find the area of the shaded region.
If the area of the circle is numerically equal to twice its circumference then what is the diameter of the circle?
The diameter of the wheels of a bus is 140 cm. How many revolutions per minute do the wheels make when the bus is moving at a speed of 72.6 km per hour?
If three circles of radius a each, are drawn such that each touches the other two, prove that the area included between them is equal to `4/25"a"^2`.
In the given figure, ABCD is a rectangle inscribed in a circle having length 8 cm and breadth 6 cm. If π = 3.14, then the area of the shaded region is:
A lawn is in the shape of a semicircle of diameter 42m. the lawn is surrounded by a flower bed of width 7m all round. Find the area of the flower bed in m2.
