Answer:
A: 274.1 (274.05)
Step-by-step explanation:
In the image it gives you the the edge lengths and the distance from the center to the middle of the edge, so to solve this we are going to act like we are solving for a right triangle.
so you need to divide the edge length by 2 (8.7/2) to get 4.35.
next you want to multiply 9 by 4.35 to get 39.15
now remember that that is not the area of a right triangle
to get the area of the triangle you divide 39.15 by 2 to get 19.575
this method will only find half a edge so to find the total area you can either multiply 19.575 by 14 to get the area of all the halves which gets you 274.05 (274.1) OR you can multiply 19.575 by 2 which gets you the full area of one of the edges which is 39.15 (yes this is the number from earlier) and multiply that by 7 (for the 7 edges) and get the same answer of 274.05 (274.1)
I hope this helped :)