Advertisements
Advertisements
Question
The radii of the inner and outer circumferences of a circular running track are 63 m and 70 m respectively. Find :
(i) the area of the track ;
(ii) the difference between the lengths of the two circumferences of the track.
Advertisements
Solution
Outer radius, r1 = 70 m
Inner radius, r2 = 63 m
∴ Area of track = `pir_1^2 - pir_2^2`
= `22/7[(70)^2 - (63)^2]`
= `22/7(70 + 63)(70 - 63)`
= `22/7 xx 133 xx 7`
= 2926 m2
Length of outer edge i.e. circumference
= `2pir_1`
= `2 xx 22/7 xx 70 = 440`m
Length of inner edge = `2pir_2`
= `2 xx 22/7 xx 63 = 396` m
Difference between lengths of two circumferences = 440 – 396 = 44 m
Hence (i) 2926 m2 (ii) 44 m
APPEARS IN
RELATED QUESTIONS
Find the area of the following circle, given that radius = 14 mm (take `pi = 22/7`).
Find the area and perimeter of a square plot of land whose diagonal is 24 m long.
An arc subtends an angle of 90° at the centre of the circle of the radius 14 cm. Write the area of minor sector thus formed in terms of π.
In the given figure, a square OABC is inscribed in a quadrant OPBQ of a circle. If OA = 20 cm, find the area of the shaded region. [Use π = 3.14.]
In the given figure, O is the centre of the bigger circle, and AC is its diameter. Another circle with AB as diameter is drawn. If AC = 54 cm and BC = 10, find the area of the shaded region.
The area of the sector of angle θ° of a circle with radius R is
The minute hand of a clock is 8 cm long. Find the area swept by the minute hand between 8.30 a.m. and 9.05 a.m.
Find the radius and circumference of a circle, whose area is :
(i) 154 cm2
(ii) 6.16 m2
A sprinkler placed at the centre of a flower garden sprays water covering a circular area. If the area watered is 1386 cm2, find its radius and diameter
The diameter of a circle whose area is equal to the sum of the areas of the two circles of radii 24 cm and 7 cm is ______.
