Math Is Fun Forum

tacowreck

Member

Registered: 2016-02-27

Posts: 4

3D Geo Problem

Let ABCDEFGH be a rectangular prism where AB = 2, AD = 3, and AE = 5. Find the volume of pyramid ACFH.

Can you please help me on how to find the base area of the pyramid?

Last edited by tacowreck (2016-03-07 16:31:31)

Bob

Administrator

Registered: 2010-06-20

Posts: 10,643

Re: 3D Geo Problem

hi tacowreck

Using Pythagoras, AH = CF = root(34)    AC = FH = root(13)       and     AF = CH = root(29)

There are three pyramids with sides root(34) root(29) root(13)  5 3 and 2  ACHD, ACFB and CFHG

and two with  sides root(34) root(29) root(13)  each twice   AFHC and  AFHE.

You can compute the area of any triangle from its sides using Heron's formula at http://www.mathisfunforum.com/viewtopic.php?id=22854

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

tacowreck

Member

Registered: 2016-02-27

Posts: 4

Re: 3D Geo Problem

Thank you. Figured it out

mr.wong

Member

Registered: 2015-12-01

Posts: 252

Re: 3D Geo Problem

Hi  tacowreck ,

What  result  did  you  get  for  the  volume ?