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 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.
The minute hand of a circular clock is 15 cm long. How far does the tip of the minute hand move in 1 hour. (Take π = 3.14)
The shape of the cross section of a canal is a trapezium. If the canal is 10 m wide at the top, 6 m wide at the bottom and the area of its cross section is `640m^2` , find the depth of the canal.
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.
Diameter of the circular garden is 42 m. There is a 3.5 m wide road around the garden. Find the area of the road.
Construct the circumcircle of the ABC when BC = 6 cm, B = 55° and C = 70°.
The area between the circumference of two concentric circles is 2464cm2. If the inner circle has a circumference of 132cm, calculate the radius of the outer circle.
A wire when bent in the form of a square encloses an area of 484cm2. If the same wire is bent into the form of a circle, find the area of the circle.
Is it true that the distance travelled by a circular wheel of diameter d cm in one revolution is 2 π d cm? Why?
Find the number of revolutions made by a circular wheel of area 1.54 m2 in rolling a distance of 176 m.
