Answer :

Given: Circumference of the circle = 31.4 cm

2\(\pi\)r = 31.4

\(\therefore r= \frac{31.4}{2×3.14} = 5cm \)

Area of the circle =\( \pi r^2 = 3.14 × 5 × 5 = 78.5 cm^2 \)
Hence, the required radius = 5 cm and area =\( 78.5 cm^2.\)

- Q.1 Find the circumference of the circles with the following radius. (Take \(\pi =\frac{22}{7} \)) (a) 14 cm (b) 28 mm (c) 21 cm
- Q.2 Find the area of the following circles, given that (Take \(\pi =\frac{22}{7} \)) (a) radius = 14 mm (b) diameter = 49 m (c) radius = 5 cm
- Q.3 If the circumference of a circular sheet is 154 m, find its radius. Also find the area of the sheet. (Take \(\pi =\frac{22}{7} \))
- Q.4 A gardener wants to fence a circular garden of diameter 21m. Find the length of the rope he needs to purchase, if he makes 2 rounds of fence. Also find the cost of the rope, if it costs Rs. 4 per meter. (Take \(\pi = \frac{22}{7} \))
- Q.5 From a circular sheet of radius 4 cm, a circle of radius 3 cm is removed. Find the area of the remaining sheet. (Take \(\pi \)= 3.14)
- Q.6 Saima wants to put a lace on the edge of a circular table cover of diameter 1.5 m. Find the length of the lace required and also find its cost if one metre of the lace costs Rs.15. (Take \(\pi \)= 3.14)
- Q.7 Find the perimeter of the adjoining figure, which is a semicircle including its diameter.
- Q.8 Find the cost of polishing a circular table-top of diameter 1.6 m, if the rate of polishing is Rs.15\( m^2. (Take \pi = 3.14) \)
- Q.9 Shazli took a wire of length 44 cm and bent it into the shape of a circle. Find the radius of that circle. Also find its area. If the same wire is bent into the shape of a square, what will be the length of each of its sides? Which figure encloses more area, the circle or the square? (Take \(\pi =\frac{22}{7} \))
- Q.10 From a circular card sheet of radius 14 cm, two circles of radius 3.5 cm and a rectangle of length 3 cm and breadth 1 cm are removed, (as shown in the given figure below). Find the area of the remaining sheet. (Take \(\pi = \frac{22}{7} \) )
- Q.11 A circle of radius 2 cm is cut out from a square piece of an aluminium sheet of side 6 cm. What is the area of the left over aluminium sheet? (Take \(\pi = 3.14)
- Q.13 A circular flower bed is surrounded by a path 4 m wide. The diameter of the flower bed is 66 m. What is the area of this path? (Take \(\pi \) = 3.14)
- Q.14 A circular flower garden has an area of\( 314 m^2. \) A sprinkler at the centre of the garden can cover an area that has a radius of 12 m. Will the sprinkler can water the entire garden? [Take\(\pi \) = 3.14]
- Q.15 Find the circumference of the inner and the outer circles, shown in the given figure. (Take \(\pi \)= 3.14)
- Q.16 How many times a wheel of radius 28 cm must rotate to go 352 m? (Take\( \pi =\frac{22}{7} \))
- Q.17 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 \(\pi \) = 3.14)

- NCERT solutions for class 7 maths chapter 1 Integers
- NCERT solutions for class 7 maths chapter 2 Fractions and Decimals
- NCERT solutions for class 7 maths chapter 3 Data Handling
- NCERT solutions for class 7 maths chapter 4 Simple Equations
- NCERT solutions for class 7 maths chapter 5 Lines and Angles
- NCERT solutions for class 7 maths chapter 6 The Triangle and its Properties
- NCERT solutions for class 7 maths chapter 7 Congruence of Triangles
- NCERT solutions for class 7 maths chapter 8 Comparing Quantities
- NCERT solutions for class 7 maths chapter 9 Rational Numbers
- NCERT solutions for class 7 maths chapter 10 Practical Geometry
- NCERT solutions for class 7 maths chapter 11 Perimeter and Area
- NCERT solutions for class 7 maths chapter 12 Algebraic Expressions
- NCERT solutions for class 7 maths chapter 13 Exponents and Powers
- NCERT solutions for class 7 maths chapter 14 Symmetry
- NCERT solutions for class 7 maths chapter 15 Visualising Solid Shapes

- NCERT solutions for class 7 science chapter 1 Nutrition in Plants
- NCERT solutions for class 7 science chapter 2 Nutrition In Animals
- NCERT solutions for class 7 science chapter 3 Fibre to Fabric
- NCERT solutions for class 7 science chapter 4 Heat
- NCERT solutions for class 7 science chapter 5 Acids Bases and Salts
- NCERT solutions for class 7 science chapter 6 Physical and Chemical Changes
- NCERT solutions for class 7 science chapter 7 Weather, Climate and Adaptations of Animals to Climate
- NCERT solutions for class 7 science chapter 8 Winds, Storms and Cyclones
- NCERT solutions for class 7 science chapter 9 soil
- NCERT solutions for class 7 science chapter 10 Respiration in Organisms
- NCERT solutions for class 7 science chapter 11 Transportation in Animals and Plants
- NCERT solutions for class 7 science chapter 12 Reproduction In Plant
- NCERT solutions for class 7 science chapter 13 Motion and Time
- NCERT solutions for class 7 science chapter 14 Electric Current and Its Effects
- NCERT solutions for class 7 science chapter 15 Light
- NCERT solutions for class 7 science chapter 16 Water: A Precious Resource
- NCERT solutions for class 7 science chapter 17 Forests: Our Lifeline
- NCERT solutions for class 7 science chapter 18 Waste Water Story