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The total surface are of a hemisphere is...

The total surface are of a hemisphere is very nearly equal to that of an equilateral triangle. The side of the triangle is how many times (approximately) of the radius of the hemisphere?

A

`((8pi)/sqrt3)0.5`

B

`((4pi)/3)0.5`

C

`(2pi sqrt3)0.5`

D

`(4pisqrt3)0.5`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the relationship between the side of an equilateral triangle and the radius of a hemisphere, given that their total surface areas are equal. ### Step-by-Step Solution: 1. **Understand the Total Surface Area of a Hemisphere**: The total surface area (TSA) of a hemisphere is given by the formula: \[ \text{TSA of Hemisphere} = 3\pi r^2 \] where \( r \) is the radius of the hemisphere. 2. **Understand the Total Surface Area of an Equilateral Triangle**: The total surface area of an equilateral triangle can be represented as: \[ \text{Area of Equilateral Triangle} = \frac{\sqrt{3}}{4} a^2 \] where \( a \) is the length of one side of the triangle. 3. **Set the Two Areas Equal**: According to the problem, the total surface area of the hemisphere is approximately equal to the area of the equilateral triangle: \[ 3\pi r^2 = \frac{\sqrt{3}}{4} a^2 \] 4. **Rearranging the Equation**: To find \( a \) in terms of \( r \), we can rearrange the equation: \[ a^2 = \frac{4 \cdot 3\pi r^2}{\sqrt{3}} \] Simplifying this gives: \[ a^2 = \frac{12\pi r^2}{\sqrt{3}} \] 5. **Taking the Square Root**: Now, take the square root of both sides to find \( a \): \[ a = \sqrt{\frac{12\pi}{\sqrt{3}}} \cdot r \] 6. **Simplifying the Expression**: We can simplify \( \sqrt{\frac{12\pi}{\sqrt{3}}} \): \[ a = \sqrt{12\pi} \cdot \frac{1}{\sqrt[4]{3}} \cdot r \] This can be further simplified to: \[ a \approx 2\sqrt{3\pi} \cdot r \] 7. **Calculating the Approximate Value**: To find the approximate numerical value, we can substitute \( \pi \approx 3.14 \): \[ a \approx 2\sqrt{3 \cdot 3.14} \cdot r \approx 2\sqrt{9.42} \cdot r \approx 2 \cdot 3.07 \cdot r \approx 6.14r \] Thus, the side of the triangle is approximately \( 6.14 \) times the radius of the hemisphere. ### Final Answer: The side of the triangle is approximately \( 6.14 \) times the radius of the hemisphere.
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