Area of a triangle in 3 space using cross product

In summary, when calculating the area of a triangle in 3 space, the order of the vectors used does not matter. This is because of the norm, which results in all combinations of vectors (ab, bc, ac) giving the same result. Thus, it does not matter which vectors are chosen as a and b in the formula 1/2||axb||.
  • #1
jlemus85
6
0
Hi all, I have a general question.

When calculating the area of a triangle in 3 space, one applies the formula

1/2||axb||. Given three vertices, a,b,c...does it matter which vectors we choose to use (ab, bc, ac) as our a b vectors?

Thanks!
 
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  • #2
First, because of the norm, it does not matter which is a and which is b: that is (1/2)||axb||= (1/2)||bxa||. That is, order doesn't matter. Now if a, b, and c are vectors forming a triangle, then c= a+ b so (1/2)||axc||= (1/2)||ax(a+b||= (1/2)||axa+ ab|= (1/2)||axb|| because axa= 0. In other words, all combinations give the same result.
 

1. What is the formula for finding the area of a triangle in 3 space using cross product?

The formula for finding the area of a triangle in 3 space using cross product is:

A = 1/2 * ||(b-a)x(c-a)||

Where a, b, and c are the three vertices of the triangle and ||v|| represents the magnitude of vector v.

2. How is the cross product used to find the area of a triangle in 3 space?

The cross product is used to find the area of a triangle in 3 space by taking the cross product of two sides of the triangle. The magnitude of this cross product is equal to the area of the parallelogram formed by the two sides. Dividing this area by 2 gives us the area of the triangle.

3. Is it necessary to use the cross product to find the area of a triangle in 3 space?

No, it is not necessary to use the cross product to find the area of a triangle in 3 space. The traditional formula of A = 1/2 * base * height can also be used to find the area of a triangle in 3 space, but only if the triangle is lying on a plane parallel to one of the coordinate planes.

4. Can the cross product be used to find the area of any shape in 3 space?

No, the cross product can only be used to find the area of a triangle in 3 space. This is because the cross product only applies to two vectors and the area of a triangle is only defined by two sides.

5. Are there any limitations to using the cross product to find the area of a triangle in 3 space?

Yes, there are a few limitations to using the cross product to find the area of a triangle in 3 space. The triangle must be lying on a plane parallel to one of the coordinate planes and the triangle cannot be degenerate (meaning it cannot have zero area). Additionally, the cross product only works for triangles in 3 space and cannot be used for triangles in higher dimensions.

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