An equilateral triangle has a semiperimeter of 6 meters. Using Heron's formula, what is the area of the triangle? Round to the nearest square meter.

[tex]\[ \text{Heron's formula: Area} = \sqrt{s(s-a)(s-b)(s-c)} \][/tex]

A. 2 square meters
B. 7 square meters
C. 20 square meters
D. 78 square meters



Answer :

To find the area of an equilateral triangle with a given semiperimeter of 6 meters, we'll follow these steps:

1. Determine the side length (a):

For an equilateral triangle, all three sides are equal. The semiperimeter [tex]\( s \)[/tex] is given by half the perimeter of the triangle, or:
[tex]\[ s = \frac{3a}{2} \][/tex]
Solving for the side length [tex]\( a \)[/tex], we get:
[tex]\[ a = \frac{2s}{3} \][/tex]
Substituting [tex]\( s = 6 \)[/tex] into the equation:
[tex]\[ a = \frac{2 \times 6}{3} = 4 \, \text{meters} \][/tex]

2. Apply Heron's formula:

Heron's formula for the area [tex]\( A \)[/tex] of a triangle is given by:
[tex]\[ A = \sqrt{s(s-a)(s-b)(s-c)} \][/tex]
Since this is an equilateral triangle, all sides are equal (i.e., [tex]\( a = b = c \)[/tex]). Hence:
[tex]\[ A = \sqrt{s(s-a)(s-a)(s-a)} \][/tex]

3. Substitute the known values:

Using [tex]\( s = 6 \)[/tex] and [tex]\( a = 4 \)[/tex]:
[tex]\[ A = \sqrt{6 \times (6-4) \times (6-4) \times (6-4)} \][/tex]
Simplify inside the square root:
[tex]\[ A = \sqrt{6 \times 2 \times 2 \times 2} = \sqrt{6 \times 8} = \sqrt{48} \][/tex]

4. Calculate the area:

[tex]\[ A = \sqrt{48} \approx 6.928203230275509 \, \text{square meters} \][/tex]

5. Round the area to the nearest square meter:

[tex]\[ \text{Rounded area} \approx 7 \, \text{square meters} \][/tex]

Therefore, the area of the equilateral triangle is approximately 7 square meters. The correct choice from the given options is 7 square meters.

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