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Question

Consider the following for this Question :

Two circles with centres at $O_1$ and $O_2$ touching each other are placed inside a rectangle of sides 9 cm and 8 cm as shown in the figure given below.

What is the area of the shaded region?
 

This question was previously asked in
CDS 2 2024 Maths Question Paper (01-Sep-2024)
The correct answer is
$\frac{240 - 10\pi - \pi\theta}{24}$ square unit

To find the area of the shaded region, let's analyze the problem using the given information and diagram.

We have two circles touching each other inside a rectangle with sides 9 cm and 8 cm. The shaded region is part of the rectangle outside these circles.

The strategy is to first calculate the area of the rectangle and then subtract the combined area of the circles from it.

  1. Calculate the area of the rectangle:
    \(Area_{\text{rectangle}} = \text{length} \times \text{breadth} = 9 \, \text{cm} \times 8 \, \text{cm} = 72 \, \text{cm}^2\).
  2. Next, since the circles are touching each other, the combined circles form a straight diameter connecting the centers \(O_1\) and \(O_2\). Assuming equal radius \(r\) for both circles, this makes each diameter (and hence \(2r\)) fit the width of the rectangle spanning 9 cm.
  3. Given they are touching, the condition will be:
    \(2r = 9/2 = 4.5 \, \text{cm}\), which implies \(r = 2.25 \, \text{cm}\).
  4. Now calculate the total area of both circles:
    \(Area_{\text{circles}} = 2 \times \pi r^2 = 2 \times \pi (2.25)^2 = 2 \times \pi \times 5.0625 = 10.125\pi \, \text{cm}^2\).
  5. Finally, find the area of the shaded region by subtracting the area of the circles from the area of the rectangle:
    \(Area_{\text{shaded}} = 72 - 10.125\pi \, \text{cm}^2\).
  6. Given the options, we match the derived formula:

The correct answer thus corresponds to:

\(\frac{240 - 10\pi - \pi\theta}{24}\text{ square unit}\).

Therefore, given our derived formula and the matching option, the correct answer is:

\(\frac{240 - 10\pi - \pi\theta}{24}\text{ square unit}\).

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Similar Questions

  1. The chord AB of a circle with centre at O is \(2\sqrt{3}\) times the height of the minor segment. If P is the area of the sector OAB and Q is the area of the minor segment of the circle, then what is the approximate value of \(\frac{P}{Q}\)?
    (Take \(\sqrt{3} = 1.7\) and \(\pi = 3.14\))
  2. What is the area of the shaded region?
     

  3. What is the ratio of the area of the shaded region to the area of the non-shaded region?

  4. What is the radius of the circle with centre at $O_1$?
     

  5. What is the radius of the circle with centre at $O_2$?
     

  6. What is the sum of the areas of the two circles?

  7. What is the area of the region between two concentric circles, if the length of a chord of the outer circle touching the inner circle at a particular point of its circumference is 14 cm?
    (Take \(\pi = \frac{22}{7}\))
  8. What is the ratio of the area of the shaded region to that of the non-shaded region?
     

  9. In a quarter circle of radius R, a circle of radius \(r\) is inscribed. What is the ratio of R to \(r\)?
  10. What is the perimeter of the shaded region?


Important Questions from Circles

  1. The sum of the radius and diameter of a circle is 84 cm. What is the circumference of this circle?

  2. The maximum area of a right-angled triangle inscribed in a circle of radius r is

  3. The tangent at a point C of a circle and diameter AB when extended intersect at D, if ∠DCA = 110°, then ∠CBA is equal to

  4. The equation of a circle with diameters are 2x - 3y + 12 = 0 and x + 4y - 5 = 0 and area of 154 sq. units is

  5. The internal center of similitude of two circles $ (x - 1)^2 + (y - 3)^2 = 4 $ and $ (x + 5)^2 + (y - 9)^2 = 16 $ is

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