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The perimeter of an equilateral triangle...

The perimeter of an equilateral triangle is equal to the circumference of a circle. The ratio of their areas is
(Use `pi = (22)/(7)`)

A

`22 : 21sqrt(3)`

B

`21 : 22sqrt(3)`

C

`21 : 22sqrt(2)`

D

`22 : 21sqrt(2)`

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The correct Answer is:
To solve the problem, we need to find the ratio of the areas of an equilateral triangle and a circle, given that their perimeter and circumference are equal. ### Step-by-Step Solution: 1. **Define Variables:** Let the side length of the equilateral triangle be \( A \) and the radius of the circle be \( R \). 2. **Perimeter of the Equilateral Triangle:** The perimeter \( P \) of an equilateral triangle is given by: \[ P = 3A \] 3. **Circumference of the Circle:** The circumference \( C \) of a circle is given by: \[ C = 2\pi R \] 4. **Set the Perimeter Equal to the Circumference:** According to the problem, the perimeter of the triangle is equal to the circumference of the circle: \[ 3A = 2\pi R \] 5. **Express \( A \) in terms of \( R \):** Rearranging the equation gives: \[ A = \frac{2\pi R}{3} \] 6. **Area of the Equilateral Triangle:** The area \( A_T \) of an equilateral triangle is given by: \[ A_T = \frac{\sqrt{3}}{4} A^2 \] Substituting \( A \) from the previous step: \[ A_T = \frac{\sqrt{3}}{4} \left(\frac{2\pi R}{3}\right)^2 = \frac{\sqrt{3}}{4} \cdot \frac{4\pi^2 R^2}{9} = \frac{\sqrt{3}\pi^2 R^2}{9} \] 7. **Area of the Circle:** The area \( A_C \) of the circle is given by: \[ A_C = \pi R^2 \] 8. **Ratio of Areas:** Now, we need to find the ratio of the area of the triangle to the area of the circle: \[ \text{Ratio} = \frac{A_T}{A_C} = \frac{\frac{\sqrt{3}\pi^2 R^2}{9}}{\pi R^2} \] Simplifying this gives: \[ \text{Ratio} = \frac{\sqrt{3}\pi^2}{9\pi} = \frac{\sqrt{3}\pi}{9} \] 9. **Substituting \( \pi \):** Using \( \pi = \frac{22}{7} \): \[ \text{Ratio} = \frac{\sqrt{3} \cdot \frac{22}{7}}{9} = \frac{22\sqrt{3}}{63} \] 10. **Final Ratio:** To express the ratio in a more recognizable form, we can multiply both the numerator and the denominator by 7: \[ \text{Final Ratio} = \frac{22\sqrt{3}}{63} \cdot \frac{7}{7} = \frac{154\sqrt{3}}{441} \] This can be simplified further, but the answer can be expressed in terms of the options given.
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