Please help me with this!

360 — A

Step-by-step explanation:

This is a square based pyramid. Which means that all of the triangles have the same area. All you need to do is find the area of one triangle, multiply it by 4, and add that to the area of the square base.

Step 1) FIND THE AREA OF ONE TRIANGLE

Imagine the triangle as a flat 2D shape. The height of this shape would be 13km, that mush is given to us. The length is also given, 10km.

How to find the area of a triangle:

Multiply the height times the width and divide the result by 2.

1. 13 x 10 = 130

2. 130/2 = 65

The area of this triangle is 65km squared.

Step 2) MULTIPLY BY 4

65 x 4 = 260

Step 3) FIND THE AREA OF THE SQUARE

When you find the area of a square, all you need is the length of one edge. That is 10km in this case.

Multiply this length by itself,

10 x 10 = 100

GETTING THE FINAL ANSWER

Add all your results :

260 + 100 = 360