# Thread: [SOLVED] Geometry HELP!!! Triangular Pyramid

1. ## [SOLVED] Geometry HELP!!! Triangular Pyramid

Hey,

I have a questions that I can't seem to answer, and I'm sure its pretty simple...I am very weak in Math, and I'm learning this on my own (homeschool). So here it is:

I have to include the proper units ex. cm, in, m, etc....and I have to show all work!

1. Find the lateral area of a regular triangular pyramid with base edge 3 in and slant height 4 in.

2. This image demonstrates what base edge and slant height are.

Look at the lateral triangle that slant height is drawn. Its base is 3 inches, like other base edges. All base edges are equivalent since it's a regular triangular pyramid.

And we know that slant height is 4 inches. Aha! It's so easy, we have the base and the height of one of the lateral triangles. Its area is $4x3/2 = 6$ square inches.

If the area of one lateral triangle is 6 square inches, and there are 3 of them, what can the total lateral area be? As you see, there are 3 equivalent lateral triangles, each of them being 6 square inches. Then the total area is $6x3 = 18$ square inches