Answer:
Step-by-step explanation:
Surface area for a pyramid is pretty imple, you just add the area of each face up. Since all the faces are equilateral, you just need to find the area of one and multiply it by 4 since there are 4 faces on a triangular pyramid.
The area of a triangl is .5 times the base times the height. Since they are equilateral, the base length is the same as the other two sides, and it says all the sides are 12 mm. now the height of each triangle would be a little more tricky, except they give us the slant height, which for the equilateral triangle face is the height, so it gives us all the information.
First, area of one triangle.
.5 * 12 * 10.1 = 60.6
There are four faces with that area, so the surface area is
4*60.6 = 242.4 mm
