Advertisements
Advertisements
प्रश्न
The diameter of two circles are 28 cm and 24 cm. Find the circumference of the circle having its area equal to sum of the areas of the two circles.
उत्तर
Let R be the radius of the big circle.
The radii of two circles are
r1 = `"d"_1/(2) = (28)/(2) = 14"cm"`
and
r2 = `"d"_2/(2) = (24)/(2) = 12"cm"`
Now,
Area of big circle
= Sum of areas of circles of radii r1 and r2
⇒ πR2 = πr12 + πr22
⇒ R2 = r12 + r22
⇒ R2 = 142 + 122
⇒ R2 = 196 + 144
⇒ R2 = 340
⇒ R = 18.4
∴ Circumference of big circle
= 2πR
= `2 xx (22)/(7) xx 18.4`
= 115.65cm2.
APPEARS IN
संबंधित प्रश्न
The sum of the radii of two circles is 140 cm and the difference of their circumferences in 88 cm. Find the diameters of the circles.
Choose the correct alternative answer for the following question.
Two circular pieces of equal radii and maximum area, touching each other are cut out from a rectangular cardboard of dimensions 14 cm ⨯ 7 cm. Find the area of the remaining cardboard.
The radius of a circle is 5 m. Find the circumference of the circle whose area is 49 times the area of the given circle.
The circumference of a circle exceeds its diameter by 18 cm. find the radius of the circle.
The inner circumference of a circular track is 264 m and the width of the track is 7 m. Find:
(i) the radius of the inner track.
(ii) the radius of the outer circumference.
(iii) the length of the outer circumference.
(iv) the cost of fencing the outer circumference at the rate of ₹50 per m.
Complete the table below.
| Radius (r) | Diameter (d) | Circumference (c) |
| 7 cm | ______ | _______ |
The sum of the circumference and diameter of a circle is 176 cm. Find the area of the circle.
The cost of decorating the circumference of a circular lawn of a house at the rate of ₹ 55 per metre is ₹ 16940. What is the radius of the lawn?
