Advertisements
Advertisements
प्रश्न
The areas of two circles are in the ratio 49 : 64. Find the ratio of their circumferences.
Advertisements
उत्तर
Given, the area of two circles are in the ratio 49 : 64
Area of a circle = πr2
Let area of the first circle = `pir_1^2`
And area of the second circle = `pir_2^2`
According to the question,
`49/64 = (pir_1^2)/(pir_2^2)`
⇒ `49/64 = r_1^2/r_2^2`
⇒ `(7)^2/(8)^2 = r_1^2/r_2^2`
⇒ `(7/8)^2 = (r_1/r_2)^2`
∴ r1 = 7 and r2 = 8
The ratio of circumferences of these two circles
= `(2pir_1)/(2pir_2)` ...[∵ Circumference of circle = 2πr]
= `r_1/r_2`
= `7/8`
Hence, required ratio is 7 : 8
APPEARS IN
संबंधित प्रश्न
Find the area, in square metres, of the trapezium whose bases and altitude is as under:
bases = 28 cm and 3 dm, altitude = 25 cm
Find the sum of the lengths of the bases of a trapezium whose area is 4.2 m2 and whose height is 280 cm.
Mohan wants to buy a trapezium shaped field. Its side along the river is parallel and twice the side along the road. If the area of this field is 10500 m2 and the perpendicular distance between the two parallel sides is 100 m, find the length of the side along the river.
The parallel sides of a trapezium are 25 cm and 13 cm; its nonparallel sides are equal, each being 10 cm, find the area of the trapezium.
Find the area of a trapezium whose parallel sides are 25 cm, 13 cm and the other sides are 15 cm each.
Find the area of the pentagon shown in fig. 20.48, if AD = 10 cm, AG = 8 cm, AH = 6 cm, AF = 5 cm, BF = 5 cm, CG = 7 cm and EH = 3 cm.
Find the missing values.
| Height 'h' | Parallel side 'a` | Parallel side 'b` | Area |
| 10 m | 12 m | 20 m |
Find the missing values.
| Height 'h' | Parallel side 'a` | Parallel side 'b` | Area |
| 13 cm | 28 cm | 492 sq.cm |
Arivu has a land ABCD with the measurements given in the figure. If a portion ABED is used for cultivation (where E is the mid-point of DC), find the cultivated area.
The area of a trapezium with equal non-parallel sides is 168 m2. If the lengths of the parallel sides are 36 m and 20 m, find the length of the non-parallel sides.
