What is the Linear Combination of Vectors for the Centroid of a Triangle?

In summary, the conversation discusses finding the vector SM as a linear combination of A, B, and C, with M being the midpoint of BD and S being the center of triangle ABC. The suggested solution involves expressing point S as a linear combination and avoiding working with angles, using techniques like averages instead. The correct values for points M and S are (a+c)/2 and (0+a+b)/3, respectively. Additional reading on the centroid is also mentioned.
  • #1
lucfuture
7
0

Homework Statement


http://delphi.zsg-rottenburg.de/gif/1la1_pyramide.gif
It says "M is the midpoint of BD and S is the center of triangle ABC. Express vector SM as a linear combination of A, B, and C."


The Attempt at a Solution


I think I am correct in saying that SM is half the magnitude of vector C and has the same angle with respect to the plane that triangle ABC is in.
 
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  • #2
You mean a linear combination of a, b and c !
My attempt would be to write to point S as a lin.comb. and also the point M as a lin.comb. I would also avoid working with angles, uses techniques like averages instead.
 
  • #3
Outlined said:
You mean a linear combination of a, b and c !
My attempt would be to write to point S as a lin.comb. and also the point M as a lin.comb. I would also avoid working with angles, uses techniques like averages instead.
You are correct! sorry. so S would be 1/2a+1/2b and M would be 31/2/2 a+31/2/2 c?
 
  • #5
Ok a agree that M is (a+c)/2. For S I would say it is (a+b)/4 because M' would be (a+b)/2 by the same method we got M. And S is half the distance that M' is from point A.

does that make sense?
 
  • #6
And then you would use vector subtraction of vectors AM - AS to get the answer?
 
  • #7
Well, S = (0 + a + b) / 3. Also have a look at that link, the middle is called the centroid.
 

What is a linear combination of vectors?

A linear combination of vectors is a mathematical operation in which two or more vectors are added together after being multiplied by certain coefficients. The result is a new vector that is a combination of the original vectors.

What is the purpose of performing a linear combination of vectors?

The purpose of performing a linear combination of vectors is to find a new vector that lies in the same span or direction as the original vectors. This allows for more complex calculations and representations in mathematics and science.

How is a linear combination of vectors calculated?

To calculate a linear combination of vectors, you must first determine the coefficients that will be used to multiply each vector. Then, multiply each vector by its corresponding coefficient and add the resulting vectors together. The resulting vector is the linear combination of the original vectors.

What are some applications of linear combinations of vectors?

Linear combinations of vectors are used in a variety of fields, including physics, engineering, and computer graphics. They are particularly useful in representing and solving systems of linear equations, as well as in mapping transformations in geometry.

Can any two vectors be used in a linear combination?

Yes, any two vectors can be used in a linear combination. However, the resulting vector will only be in the span of the two original vectors if they are linearly independent (not parallel or collinear). Otherwise, the resulting vector will be a scalar multiple of one of the original vectors.

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