Advertisements
Advertisements
Question
Find the circumference of the circle whose area is 25times the area of the circle with radius 7cm.
Advertisements
Solution
The Area of a Circle with radius r = πr2
The Area of a Circle with radius7 = π(7)2
The Area of the bigger Circle
= 25 x π(7)2
= π(72 x 52)
= π(352)
Let radius of the bigger Circle = R
R2 = π(352)
⇒ radius of the bigger Circle = 35
The Circumference of a Circle with radius r = 2πr
The Circumference of a Circle with radiu 35r
= 2π x 35
= 220cm.
APPEARS IN
RELATED QUESTIONS
The radii of two circles are 19 cm and 9 cm respectively. Find the radius of the circle which has circumference equal to the sum of the circumferences of the two circles.
Find the area of a right – angled triangle, the radius of whose, circumference measures 8 cm and the altitude drawn to the hypotenuse measures 6 cm.
A horse is placed for grazing inside a rectangular field 70 m by 52 m. It is tethered to one corner by a rope 21 m long. On how much area can it graze? How much area is left ungrazed?
The circumference of a circle is equal to the sum of the circumference of two circles having diameters 36 cm and 20 cm. The radius of the new circle is
The radius of the circle is given below; find the area.
28 cm
The diameter of a cycle wheel is `4 5/11` cm. How many revolution will it make in moving 6.3 km ?
The shaded portion of the figure, given alongside, shows two concentric circles. If the circumference of the two circles is 396 cm and 374 cm, find the area of the shaded portion.
The circumference o a garden roller is 280cm. How many revolutions does it make in moving 490m?
Circumference of a circle is always ______.
Find the radius of a circle whose circumference is equal to the sum of the circumferences of two circles of radii 15 cm and 18 cm.
