Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

Pages: **1**

**samuel.bradley.99****Member**- Registered: 2016-03-16
- Posts: 51

Given a tetrahedron IABC where all its edges have equal length x, we take points A1 on IA, such as IA1=1/2 IA, point B1 on IB such as IB1=2/3 IB and point C1 on IC such as IC1=3/4 IC.

Find the volume of tetrahedron IA1B1C1 in relation to a.

Sorry, I accidentally cut off half the wording

*Last edited by samuel.bradley.99 (2017-07-31 00:47:58)*

Offline

**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,322

hi samuel.bradley.99

I've been away so I've only just seen this problem. I had a vague memory that the volume of a tetrahedron could be calculated using vector cross and dot products. A quick 'google' took me to this page:

https://math.stackexchange.com/question … ot-product

Your tetrahedron is a regular one by the way which fixes the directions of the vectors IA, IB and IC. So it looks like you can use this formula to get a result. But post back if you need a quick lesson in cross and dot products.

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

Offline

Pages: **1**