+0  
 
0
170
4
avatar

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

Guest Apr 12, 2017
Sort: 

4+0 Answers

 #1
avatar+5552 
+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
avatar+91229 
+1

Thanks guest 

 

Could you please derive that formula ?

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

Melody  Apr 12, 2017
edited by Melody  Apr 12, 2017
 #4
avatar+5552 
+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
edited by hectictar  Apr 12, 2017
 #3
avatar+79741 
+1

"L.A" of a square-based pyramid  

 

We have four triangles each with base edge "b"   and a slant height, "h"

 

And....the lateral surface area  =

 

4 * (1/2) b * h   =

 

2bh 

 

But.....the perimeter  = 4b

 

So

 

2bh  =  

 

(1/2) 4b * h  =

 

(1/2) *perimeter * slant height of each face

 

 

cool cool cool

CPhill  Apr 12, 2017

20 Online Users

avatar
avatar
avatar
avatar
avatar
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details