Advertisements
Advertisements
प्रश्न
The area between the circumference of two concentric circles is 2464cm2. If the inner circle has a circumference of 132cm, calculate the radius of the outer circle.
Advertisements
उत्तर
We know,
The area of the ring between two concentric circles equal the area of the larger circle minus the area of smaller circle. Let the radius of the outer and inner ring be R and r respectively
The Area of a Circle with radius r = πr2
area of the ring between two concentric circle
= π(R2 - r2)
= 2464cm2
The Circumference of a Circle with radius r = 2πr
The Circumference of the inner Circle with radius r = 132
2πr = 132
⇒ r = 21cm
π(R2 - 212) = 2464
⇒ `(22)/(7)("R"^2 - 441)` = 2464
⇒ (R2 - 441) = 784
⇒ R2 = 1225
⇒ R = 35cm.
APPEARS IN
संबंधित प्रश्न
A wire is looped in the form of a circle of radius 28 cm. It is re-bent into a square form. Determine the length of the side of the square.
A doorway is decorated as shown in the figure. There are four semi-circles. BC, the diameter of the larger semi-circle is of length 84 cm. Centres of the three equal semicircles lie on BC. ABC is an isosceles triangle with AB = AC. If BO = OC, find the area of the shaded region. (Take `pi = 22/7`)
Find the circumferences of a circle whose radius is 7 cm.
Find the perimeter of a semicircular protractor whose diameter is 14 cm.
Find the area of a quadrant of a circle whose circumference is 88 cm.
A bucket is raised from a well by means of a rope wound round a wheel of diameter 35 cm. If the bucket ascends in 2 minutes with a uniform speed of 1.1 m per sec, calculate the number of complete revolutions the wheel makes in raising the bucket.
Sand from a cylindrical bucket 32 cm in height and 18 cm in radius is poured onto the ground making a conical heap 24 cm high. Find the radius of the conical heap.
Find the diameter of the sphere for the following :
Surface Area = 221. 76 cm2
The radius of a circular garden is 56 m. What would it cost to put a 4-round fence around this garden at a rate of 40 rupees per metre?
Ishika has designed a small oval race track for her remote control car. Her design is shown in the figure. What is the total distance around the track? Round your answer to the nearest whole cm.
