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A wire in the form of a rectangle 18.7 c...

 A wire in the form of a rectangle 18.7 cm long and 14.3 cm wide is reshaped and bent into the form of a circle. Find the radius of the circle so formed.

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To find the radius of the circle formed by reshaping a wire in the form of a rectangle, we can follow these steps: ### Step-by-Step Solution: 1. **Calculate the Perimeter of the Rectangle**: The perimeter (P) of a rectangle can be calculated using the formula: \[ P = 2 \times (l + b) \] where \( l \) is the length and \( b \) is the breadth. Given: - Length \( l = 18.7 \, \text{cm} \) - Breadth \( b = 14.3 \, \text{cm} \) Substitute the values: \[ P = 2 \times (18.7 + 14.3) = 2 \times 33 = 66 \, \text{cm} \] 2. **Relate the Perimeter of the Rectangle to the Circumference of the Circle**: The perimeter of the rectangle is equal to the circumference (C) of the circle formed by the wire. \[ C = 66 \, \text{cm} \] 3. **Use the Circumference Formula to Find the Radius**: The circumference of a circle can be expressed as: \[ C = 2 \pi r \] where \( r \) is the radius and \( \pi \) can be approximated as \( \frac{22}{7} \). Set the circumference equal to the calculated perimeter: \[ 66 = 2 \times \frac{22}{7} \times r \] 4. **Solve for the Radius \( r \)**: Rearranging the equation to isolate \( r \): \[ r = \frac{66 \times 7}{2 \times 22} \] Simplifying the right side: \[ r = \frac{462}{44} = \frac{21}{2} = 10.5 \, \text{cm} \] ### Final Answer: The radius of the circle formed is \( 10.5 \, \text{cm} \). ---
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RS AGGARWAL-MENSURATION-EXERCISE 20E
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  2. Find the circumference of a circle of radius 15 cm. [Take pi = 3.14.]

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  3. Find the radius of a circle whose circumference is 57.2 cm.

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  4. Find the diameter of a circle whose circumference is 63.8 m.

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  6. The ratio of the radii of two circles is 5:3. Find the ratio of their ...

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  9. The inner circumference of a circular track is 330 m. The track is 10....

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  11. A piece of wire is bent in the shape of an equilateral triangle each o...

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  12. A rhombus has the same perimeter as the circumference of a circle. If ...

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  13. A wire in the form of a rectangle 18.7 cm long and 14.3 cm wide is res...

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  14. A wire is looped in the form of a circle of radius 35 cm. If it is reb...

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  15. A well of diameter 140 cm has a stone parapet around it. If the length...

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  16. Find the distance covered by the wheel of a bus in 2000 rotations if t...

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  17. The diameter of the wheel of a cycle is 70 cm. How far will it go in 2...

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