Advertisements
Advertisements
प्रश्न
Find the area of a flat circular ring formed by two concentric circles (circles with the same centre) whose radii are 9 cm and 5 cm.
Advertisements
उत्तर
External radius, r1 = 9 cm
Internal radius, r2 = 5 cm
Area of ring = `pir_1^2 - pir_2^2`
= `pi(r_1^2 - r_2^2)`
= `pi(9^(2) - 5^(2))`
= `22/7[81 - 25]`
= `22/7 xx 56`
= 176 cm2
APPEARS IN
संबंधित प्रश्न
The cost of painting the four walls of a room 12 m long at `₹ 30 per m^2 is ₹ 7560 per m^2` and the cost of covering the floor with the mat at ₹` 25 per m^2 is ₹ 2700 `. find the dimensions of the room.
The cost of fencing a square lawn at ₹ 14 per meter is ₹ 28000. Find the cost of mowing the lawn at ₹ 54 100 per `m^2`
The outer circumference of a circular race-track is 528 m . The track is everywhere 14 m wide. Calculate the cost of levelling the track at the rate of 50 paise per square metre.
`(use pi=22/7). `
In the following figure, the boundary of the shaded region consists of four semi-circular arcs, the smallest two being equal. If the diameter of the largest is 14 cm and of the smallest is 3.5 cm, find
- the length of the boundary.
- the area of the shaded region.
What is the area of a sector of a circle of radius 5 cm formed by an arc of length 3.5 cm?
The short and long hands of a clock are 4 cm and 6 cm long respectively. Find the sum of distances travelled by their tips in 2 days.
On decreasing the radius of a circle by 30%, its area is decreased by
Find the area of the shaded portion in each of the following diagrams:
(i)
(ii)
A wire, when bent in the form of a square; encloses an area of 196 cm2. If the same wire is bent to form a circle; find the area of the circle.
A piece of wire of length 108 cm is bent to form a semicircular arc bounded by its diameter. Find its radius and area enclosed.
