# Regular pyramid

• Nov 27th 2010, 03:27 AM
regdude
Regular pyramid
Hi!
Yesterday we had a exercise in geometry, it was said:
A regular triangle pyramid with all of its edges 5cm long. There is a smaller triangle that is cutting the edge in half. Need to calculate volume and full surface area.
Here is a small picture of the figure -
http://img337.imageshack.us/img337/9536/pyrl.jpg

As far as I could figure out this one, the bigger triangle is 2 times bigger then the smaller one, area is 2^2 times bigger.
• Nov 27th 2010, 05:35 AM
skeeter
Quote:

Originally Posted by regdude
Hi!
Yesterday we had a exercise in geometry, it was said:
A regular triangle pyramid with all of its edges 5cm long. There is a smaller triangle that is cutting the edge in half. Need to calculate volume and full surface area.
Here is a small picture of the figure -
http://img337.imageshack.us/img337/9536/pyrl.jpg

As far as I could figure out this one, the bigger triangle is 2 times bigger then the smaller one, area is 2^2 times bigger.

correct, and the volume of the larger would be \$\displaystyle 2^3\$ times as large.

here is a link to all kinds of good info re: tetrahedrons ...

Tetrahedron -- from Wolfram MathWorld
• Nov 27th 2010, 06:18 AM
regdude