Advertisements
Advertisements
Question
Find the radius and area of the circle which has circumference equal to the sum of circumferences of the two circles of radii 3 cm and 4 cm respectively.
Advertisements
Solution
Let R be the radius of the big circle.
The radii of two circles are r1 = 3cm and r2 = 4cm
Now,
Circumference of big circle
= Sum of circumference of circles of radii r1 and r2
⇒ 2πR = 2πr1 + 2πr2
⇒ R = r1 + r2
⇒ R
= 3 + 4
= 7cm
∴ Area of big circle
= πR2 = `(22)/(7) xx 7 xx 7`
= 154cm2.
APPEARS IN
RELATED QUESTIONS
The area of circle, inscribed in equilateral triangle is 154 cms2. Find the perimeter of
triangle.
A square water tank has its side equal to 40m, there are 4 semicircular flower beds grassy plots all around it. Find the cost of turfing the plot at Rs 1.25/sq.m
The circumferences of two circles are in the ratio 2: 3. What is the ratio between their areas?
A boy is cycling in such a way that the wheels of his bicycle are making 140 revolutions per minute. If the diameter of a wheel is 60 cm, calculate the speed (in km/h) at which the boy is cycling.
Find the area and perimeter of the circle with the following:
Diameter= 35 cm
Find the volume and the surface area of the spheres in the following :
Radius= 2.1 cm
In the given figure, the area of the shaded portion is 770 cm2. If the circumference of the outer circle is 132 cm, find the width of the shaded portion.
A wire bent in the form of an equilateral triangle has an area of `121sqrt(3)"cm"^2`. If the same wire is bent into the form of a circle, find the area enclosed by the wire.
A 4.2m wide road surrounds a circular plot whose circumference is 176m. Find the cost of paving the road at Rs.75per m2.
The area of a quadrant of a circle whose circumference is 22 cm, is ____________.
