Question

|25 POINTS| Suppose you have one pyramid with a base that is 10 meters long and 10 meters wide with a slant that is 15 meters. Now, if the length of the base is increased to 15 meters, what is the difference in the surface area between the new pyramid and the old pyramid?

125 meters squared.
525 meters squared.
600 meters squared.
400 meters squared.

Answer 1

First pyramid is = 400 meters squared

A= 10²+4*1/2*10*15= 400 m²

second pyramid = 675 meters squared

A= 10*15+2*1/2*15*15+2*1/2*10*15= 525 m²

Subtract the two =

525- 400= 125 m²

Answer 2

125 meters squared

Explanation:

Surface area of initial pyramid:

• A= 10²+4*1/2*10*15= 400 m²

Surface area of extended pyramid:

• A= 10*15+2*1/2*15*15+2*1/2*10*15= 525 m²

The difference is:

• 525- 400= 125 m²