Advertisements
Advertisements
Question
Find the area of a ring-shaped region enclosed between two concentric circles of radii 20 cm and 15 cm.
Solution
r1 = 15 cm; r2 = 20 cm
Area of the ring = `pi "r"_2^2 - pi "r"_1^2`
`= pi ["r"_2^2 - "r"_1^2]`
`= 22/7 [(20)^2 - (15)^2]`
`= 22/7 [(20 + 15)(20 - 15)]`
`= 22/7 [35 xx 5]`
`= 110 xx 5`
= 550 cm2
APPEARS IN
RELATED QUESTIONS
The circumference of a circle is 31.4 cm. Find the radius and the area of the circle? (Take π = 3.14)
Find the perimeter and area of the quadrilateral ABCD in which AB = 17 cm, AD = 9 cm, CD = 12 cm, ∠ACB=90° and AC = 15 cm.
A child makes a poster on a chart paper drawing a square ABCD of side 14 cm. She draws four circles with centre A, B, C and D in which she suggests different ways to save energy. The circles are drawn in such a way that each circle touches externally two of the three remaining circles (in the following figure). In the shaded region she write a message 'Save Energy'. Find the perimeter and area of the shaded region.
(Use π = 22/7)
Find the area of the largest triangle that can be inscribed in a semi-circle of radius runits.
The hour hand of a clock is 6 cm long. The area swept by it between 11.20 am and 11.55 am is
A square is inscribed in a circle. Find the ratio of the areas of the circle and the square.
The area of a sector of a circle with radius r, making an angle of x° at the centre is
Two circles touch each other externally. The sum of their areas is 58πcm2 and the distance between their centres us 10cm. Find the radii of the two circles.
If the radius of a circle is tripled, the area becomes ______.
Area of a quadrant of a circle of radius 7 cm is ______.
