CK-12 Geometry-Concepts

http://www.ck12.org Chapter 11. Surface Area and Volume

82 + 242 =l^2

64 + 576 =l^2

640 =l^2

l=

√

640 = 8

√

10

Example B

Find the surface area of the pyramid from Example A.

The surface area of the four triangular faces are 4

( 1

2 bl

)

= 2 ( 16 )

(

8

√

10

)

= 256

√

10. To find the total surface area,
    we also need the area of the base, which is 16^2 =256. The total surface area is 256

√

10 + 256 ≈ 1065 .54.

Example C

Find the volume of the pyramid.

V=^13 ( 122 ) 12 = 576 units^3

Watch this video for help with the Examples above.

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/52643

CK-12 Foundation: Chapter11PyramidsB

Concept Problem Revisited

The original volume of the pyramid is^13 ( 7062 )( 407. 5 )≈ 67 , 704 , 223. 33 f t^3.

Vocabulary

Apyramidis a solid with onebaseandlateral facesthat meet at a commonvertex.The edges between the lateral

faces arelateral edges.The edges between the base and the lateral faces arebase edges.