Answer:
340 ft²
Step-by-step explanation:
From the diagram, we can see that the shape is made up of a square and 4 triangles. (We know it's a square as its width equals its length).
First, find the area of the square.
Area of a square = width x length = 10 x 10 = 100 ft²
All the triangles are the same, so we need to find the area of one of the triangles and multiply it by 4.
Area of a triangle = 1/2 x base x height = 1/2 x 10 x 12 = 60 ft²
So the total area of all 4 triangles = 4 x 60 = 240 ft²
Therefore the total surface area = 100 + 240 = 340 ft²
