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If the difference between areas of the circumcircle and the incircle of an equllateral triangle is 44 `cm^(2)`, then the area of the triangle is (Take `pi = (22)/(7)`)

A

`28 cm^(2)`

B

`7 sqrt3 cm^(2)`

C

`14 sqrt3 cm^(2)`

D

`21 cm^2`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the area of an equilateral triangle given that the difference between the areas of its circumcircle and incircle is 44 cm². We will follow these steps: ### Step 1: Define the side length of the equilateral triangle Let the side length of the equilateral triangle be \( a \). ### Step 2: Calculate the radius of the incircle The radius \( r \) of the incircle of an equilateral triangle is given by the formula: \[ r = \frac{a}{2\sqrt{3}} \] ### Step 3: Calculate the radius of the circumcircle The radius \( R \) of the circumcircle of an equilateral triangle is given by the formula: \[ R = \frac{a}{\sqrt{3}} \] ### Step 4: Calculate the areas of the circumcircle and incircle The area \( A_{circum} \) of the circumcircle is: \[ A_{circum} = \pi R^2 = \pi \left(\frac{a}{\sqrt{3}}\right)^2 = \pi \frac{a^2}{3} \] The area \( A_{in} \) of the incircle is: \[ A_{in} = \pi r^2 = \pi \left(\frac{a}{2\sqrt{3}}\right)^2 = \pi \frac{a^2}{12} \] ### Step 5: Set up the equation for the difference in areas According to the problem, the difference between the areas of the circumcircle and the incircle is 44 cm²: \[ A_{circum} - A_{in} = 44 \] Substituting the areas we calculated: \[ \pi \frac{a^2}{3} - \pi \frac{a^2}{12} = 44 \] ### Step 6: Simplify the equation Factor out \( \pi \): \[ \pi \left(\frac{a^2}{3} - \frac{a^2}{12}\right) = 44 \] Finding a common denominator (which is 12): \[ \frac{4a^2}{12} - \frac{a^2}{12} = \frac{3a^2}{12} \] So we have: \[ \pi \frac{3a^2}{12} = 44 \] ### Step 7: Solve for \( a^2 \) Multiply both sides by \( \frac{12}{3\pi} \): \[ a^2 = \frac{44 \times 12}{3\pi} \] ### Step 8: Substitute \( \pi = \frac{22}{7} \) Substituting the value of \( \pi \): \[ a^2 = \frac{44 \times 12}{3 \times \frac{22}{7}} = \frac{44 \times 12 \times 7}{3 \times 22} \] Simplifying: \[ = \frac{44 \times 12 \times 7}{66} = \frac{44 \times 12 \times 7}{66} = \frac{44 \times 12}{6} = 88 \times 2 = 176 \] ### Step 9: Calculate the area of the triangle The area \( A \) of an equilateral triangle is given by: \[ A = \frac{\sqrt{3}}{4} a^2 \] Substituting \( a^2 = 176 \): \[ A = \frac{\sqrt{3}}{4} \times 176 = 44\sqrt{3} \text{ cm}^2 \] ### Final Answer The area of the triangle is \( 44\sqrt{3} \text{ cm}^2 \).
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