A = (12 x 8 x 3) + (1/2 x 8 x 6.9) + (1/2 x 8 x 7 x 3)
A = 288 + 27.6 + 84
A = 399.6 m²
i think it’s is a for the first one
Answer: C
<u>Step-by-step explanation:</u>

= 
= 
= 
= 
By using <em>triangle</em> properties and the law of the cosine twice, we find that the distance between points M and N is approximately 9.8 meters.
<h3>How to determine the distance between two points</h3>
In this problem we must determine the distance between two points that are part of a triangle and we can take advantage of properties of triangles to find it. First, we determine the measure of angle L by the law of the cosine:

L ≈ 62.464°
Then, we get the distance between points M and N by the law of the cosine once again:

MN ≈ 9.8 m
By using <em>triangle</em> properties and the law of the cosine twice, we find that the distance between points M and N is approximately 9.8 meters.
To learn more on triangles: brainly.com/question/2773823
#SPJ1