i think wiki u should answe it
Chat with our AI personalities
Outer radius = a; inner radius = b; then area of the ring = pi (a2 - b2) = 90, where pi = 22/7. In view of a = 9, we have b2 = 81 - [90 x 7 / 22], the positive square root of which gives b.
That roll of carpet has the square yardage of its width measured in yards multiplied by its length measured in yards. You may need to unroll it to find the length exactly, or if you are only looking for an approximate area and hence length, you can assume the roll is made up of concentric rings of carpet, measure the diameter of each ring from the inside to the outside (to the backing of the carpet) and use these find the circumference of each ring and sum them - this sum can be calculated by summing the diameters and multiplying that sum by π. The last ring will not usually not be a full ring, so it can either be measured directly or added in as a fraction of the whole ring multiplied by its diameter.
What kind of ring stops your circulation? A wedding ring!
From memory Paris is only 115 square kilometres within the Orbital ring road.It is quite small compared with other foreign cities..(London is 1500 Square kilometres)..but has a large populaion,giving its daytime population a density of approx.28,000 per square kilometre.Paris can be walked across in a day if you are feeling fit.
Area = (pi*32)-(pi*22) = 15.708 square feet rounded to 3 d.p.