Whats L.A when your trying to find surface area of a square-based pyramid?

Guest Apr 12, 2017

#1**+2 **

LA stands for "lateral area."

Lateral area is the surface area except for the area of the base.

The lateral area of a pyramid = (1/2) * (perimeter of base) * (height)

hectictar
Apr 12, 2017

#2**+1 **

Thanks guest

Could you please derive that formula ?

(My question is only intended for the guest who posted the formula)

Melody
Apr 12, 2017

#4**+2 **

I am sorry what I said is actually not good, I should have said slant height...

But here is my explanation. You can see how that it is because if you take the triangles and lay them out like this:

Since the base of each triangle is the same length,

area of one blue triange = (1/2)(1/4 * perimeter of base)(slant height)

There are 4 triangles total that area all the same size.. so,

area of all blue triangles = 4 * (1/2)(1/4 * perimeter of base)(slant height)

area of all blue triangles = (1/2)(perimeter of base)(slant height)

hectictar
Apr 12, 2017