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The radius of a circle is 14 cm and the ...

The radius of a circle is 14 cm and the area of the sector is `102.7 cm^(2)`. Find the central angle of the sector.

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To find the central angle of the sector given the radius of the circle and the area of the sector, we can follow these steps: ### Step 1: Write down the formula for the area of a sector The area \( A \) of a sector of a circle can be calculated using the formula: \[ A = \frac{\theta}{360} \times \pi r^2 \] where: - \( A \) is the area of the sector, - \( \theta \) is the central angle in degrees, - \( r \) is the radius of the circle. ### Step 2: Substitute the known values into the formula We are given: - Radius \( r = 14 \, \text{cm} \) - Area of the sector \( A = 102.7 \, \text{cm}^2 \) Substituting these values into the formula: \[ 102.7 = \frac{\theta}{360} \times \pi \times (14)^2 \] ### Step 3: Simplify the equation First, calculate \( \pi \times (14)^2 \): \[ \pi \times (14)^2 = \pi \times 196 = 196\pi \] Thus, the equation becomes: \[ 102.7 = \frac{\theta}{360} \times 196\pi \] ### Step 4: Solve for \( \theta \) To isolate \( \theta \), multiply both sides by \( 360 \): \[ 102.7 \times 360 = \theta \times 196\pi \] Now, divide both sides by \( 196\pi \): \[ \theta = \frac{102.7 \times 360}{196\pi} \] ### Step 5: Calculate the value of \( \theta \) Using \( \pi \approx \frac{22}{7} \): \[ \theta = \frac{102.7 \times 360}{196 \times \frac{22}{7}} \] Calculating the denominator: \[ 196 \times \frac{22}{7} = \frac{4312}{7} \] Now substituting back: \[ \theta = \frac{102.7 \times 360 \times 7}{4312} \] ### Step 6: Perform the calculations Calculating \( 102.7 \times 360 \times 7 \): \[ 102.7 \times 360 = 36972 \] Then, \[ 36972 \times 7 = 258804 \] Now divide by \( 4312 \): \[ \theta = \frac{258804}{4312} \approx 60.019 \] ### Step 7: Round the answer Thus, rounding to the nearest whole number, we find: \[ \theta \approx 60^\circ \] ### Final Answer The central angle of the sector is \( 60^\circ \). ---
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NAGEEN PRAKASHAN-AREA RELATED TO CIRCLES-Exercise 12 B
  1. A pendulum swings through an angle of 30^(@) and describes an arc 8.8 ...

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  2. The perimeter of a certain sector of a circle of radius 5.7 m is 27.2 ...

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  3. The radius of a circle is 14 cm and the area of the sector is 102.7 cm...

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  4. A chord PQ of a circle of radius 10 cm makes an angle of 60^(@) at the...

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  5. The length of a wire which is tied as a boundary of a semi ciruclar pa...

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  6. AOBC is a quadrant of a circle of radius 10 cm. Calculate the area of ...

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  7. In the square ABCD with side 2a cm, four quarter circles are drawn wit...

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  8. A park is in the form of a rectangle 120 m x 100 m. At the centre of ...

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  9. In the figure semicircles are drawn with PQ, PB and BQ as diameter. PB...

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  10. In the figure, in Delta ABC, angle B = 90^(@), AB = 28 cm and BC = 21 ...

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  11. The length of the minute hand of a clock is 10.5 cm. Find the area swe...

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  12. A chord 10 cm long is drawn in the circle whose radius is 5 sqrt2 cm. ...

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  13. In a right -angle triangle, the length of the sides containing the rig...

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  14. In the given figure, ABCD is a square of side 7 cm. DPBA and DQBC are ...

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  15. In the given figure, three semicircles are drawn of diameter 10 cm, 7 ...

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  16. From a thin metallic sheet in the shape of a trapezium ABCD in which A...

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  17. A circulare arc has been with vertex of an equilateral triangle of sid...

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  18. In the adjoining figure, O is the centre of the circle with AC = 24 cm...

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  19. A round table cover has six equal designs as shown in the given figure...

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  20. In the given figure, DeltaABC is right angled at A. Find the area of t...

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