Answer: C. 400 in^2
Step-by-step explanation:
First find the surface area or the area of the base which is in the shape of a square and has a side length of 10 in. So square 10 to find the area.
Area of base: 10 * 10 = 100
Next find the area of one of the triangles.
As we could see the triangle has a slant height of 15 in and a base of 10. To find the area of a triangle we multiply the base times the height and multiply it by half.
Area of one triangle. 15 * 10 = 150 * 1/2 = 75
Since one side of the triangle has a surface area of 75 inches we will multiply it by 4 since there are four triangles to find the total surface area of the four faces.
75 * 4 = 300
We now know that the the 4 triangles surface area dd up to 300 so we will add it to the area of the base which is 100 to find the whole surface area of the figure.
300 + 100 = 400
