Advertisements
Advertisements
प्रश्न
The area of a circular ring enclosed between two concentric circles is 88 cm 2. Find the radii of the two circles, if their difference is 1 cm.
उत्तर
Let r cm be the radius of inner circle.
Radius of outer circle = (r+ 1) cm
Area of circular ring = Area of outer cirde - area of inner circle
⇒ π (r + 1)2 - π r1 = 88
⇒ π (r1 + 2r + 1) - π r2 = 88
⇒ π r1 + 2 π r + π - πr1 = 88
⇒ `22/7 (2"r" + 1) = 88`
⇒ 2r + 1 = `88 xx 7/22`
⇒ 2r + 1 = 28
⇒ 2r = 27
⇒ r = `27/2 = 13.5` cm
(r + 1) = 13.5 + 1 = 14.5 cm
Therefore, radii are 13.5 cm and 14.5 cm.
APPEARS IN
संबंधित प्रश्न
A race track is in the form of a ring whose inner circumference is 352 m, and the outer circumference is 396 m. Find the width of the track.
The inner circumference of a circular track is 220 m. The track is 7m wide everywhere. Calculate the cost of putting up a fence along the outer circle at the rate of j – 2 per metre. (Use π = 22/7)
The minute hand of a clock is 10cm long. Find the area of the face of the clock described by the minute hand between 9 A.M. and 9.35 A.M.
A car travels 1 km distance in which each wheel makes 450 complete revolutions. Find the radius of wheel.
The area of rhombus is `480cm^2` , and one of its diagonal measures 48 cm. Find
(i) the length of the other diagonal,
(ii) the length of each of the sides
(iii) its perimeter
Choose the correct alternative answer for the following question.
A cone was melted and cast into a cylinder of the same radius as that of the base of the cone. If the height of the cylinder is 5 cm, find the height of the cone.
In the given figure, ABCD is a square of side 4 cm. A quadrant of a circle of radius 1 cm is drawn at each vertex of the square and a circle of diameter 2 cm is also drawn. Find the area of the shaded region. [π = 3.14]
If the sum of the circumferences of two circles with radii R1 and R2 is equal to the circumference of a circle of radius R, then ______.
The perimeter of a sector of a circle of radius 5.6 cm is 27.2 cm. Find the area of the sector.
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.
The speed of the car is 66 km/hour. If each wheel of the car is 140 cm in diameter, find the number of revolutions made by each wheel per minute.
The radii of two circles are 48 cm and 13 cm. Find the area of the circle which has its circumference equal to the difference of the circumferences of the given two circles.
The circumference of a circle is 440 cm. Find its radius and diameter. (Take π = `22/7`)
Find the radius of the circle whose circumference is equal to the sum of the circumferences of the circles having radius 15 cm and 8 cm.
Complete the table below.
| Radius (r) | Diameter (d) | Circumference (c) |
| 7 cm | ______ | _______ |
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?
The speed of a car is 66km per hour. If each wheel of the car is 140cm in diameter, find the number if revolution made by each wheel per minute.
Find the circumference of the circle whose area is 25times the area of the circle with radius 7cm.
Area of circular garden with diameter 8 m is ______.
