Triangle LMN has sides measuring 7 meters and 6 meters, and a perimeter of 16 meters.

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

What is the area of triangle LMN? Round to the nearest square meter.

A. 3 square meters
B. 9 square meters
C. 28 square meters
D. 34 square meters



Answer :

To find the area of triangle LMN using the given information and Heron's formula, we can follow these steps:

1. Determine the third side of the triangle:
- Given the sides of the triangle are 7 meters and 6 meters, and the perimeter of the triangle is 16 meters.
- We know that the perimeter of a triangle is the sum of all its sides.
- Let the third side be denoted as [tex]\( c \)[/tex].

[tex]\[ a + b + c = 16 \][/tex]

Plugging in the given values:

[tex]\[ 7 + 6 + c = 16 \][/tex]

Solving for [tex]\( c \)[/tex]:

[tex]\[ c = 16 - 7 - 6 \][/tex]

[tex]\[ c = 3 \][/tex]

So, the sides of the triangle are 7 meters, 6 meters, and 3 meters.

2. Calculate the semi-perimeter (s):
- The semi-perimeter [tex]\( s \)[/tex] is half of the perimeter of the triangle.

[tex]\[ s = \frac{a + b + c}{2} \][/tex]

Using the values of the sides we found:

[tex]\[ s = \frac{7 + 6 + 3}{2} \][/tex]

[tex]\[ s = \frac{16}{2} \][/tex]

[tex]\[ s = 8 \][/tex]

3. Use Heron's formula to calculate the area:
- Heron's formula states that the area [tex]\( A \)[/tex] of a triangle can be found using:

[tex]\[ A = \sqrt{s(s - a)(s - b)(s - c)} \][/tex]

Plugging in the values we have:

[tex]\[ A = \sqrt{8 \left(8 - 7\right) \left(8 - 6\right) \left(8 - 3\right)} \][/tex]

Simplify inside the square root:

[tex]\[ A = \sqrt{8 \times 1 \times 2 \times 5} \][/tex]

[tex]\[ A = \sqrt{8 \times 10} \][/tex]

[tex]\[ A = \sqrt{80} \][/tex]

4. Round the area to the nearest square meter:
- Calculating the square root of 80 and rounding to the nearest whole number:

[tex]\[ \sqrt{80} \approx 8.944 \][/tex]

Rounded to the nearest square meter:

[tex]\[ \approx 9 \][/tex]

Therefore, the area of triangle LMN rounded to the nearest square meter is 9 square meters. The correct option is 9 square meters.

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