Math Problem Statement

Given the vectors v1=(1,−3,0) and v2=(−1,2,1) .

Which of the following vectors is orthogonal to both of them?

(2, -2, 6)
(3, 1, 1)
(-2, 2, 0)
(-1, 0.5, 1)

Solution

To determine which of the given vectors is orthogonal to both v1=(1,3,0)\mathbf{v_1} = (1, -3, 0) and v2=(1,2,1)\mathbf{v_2} = (-1, 2, 1), we need to find the cross product of v1\mathbf{v_1} and v2\mathbf{v_2}. The result of this cross product will give us a vector that is orthogonal to both v1\mathbf{v_1} and v2\mathbf{v_2}. We can then compare the cross product with the given options.

Step 1: Compute the cross product of v1\mathbf{v_1} and v2\mathbf{v_2}.

The cross product of two vectors v1=(v1x,v1y,v1z)\mathbf{v_1} = (v_{1x}, v_{1y}, v_{1z}) and v2=(v2x,v2y,v2z)\mathbf{v_2} = (v_{2x}, v_{2y}, v_{2z}) is given by:

v1×v2=(v1yv2zv1zv2y,v1zv2xv1xv2z,v1xv2yv1yv2x)\mathbf{v_1} \times \mathbf{v_2} = \left( v_{1y}v_{2z} - v_{1z}v_{2y}, v_{1z}v_{2x} - v_{1x}v_{2z}, v_{1x}v_{2y} - v_{1y}v_{2x} \right)

Substitute the components of v1=(1,3,0)\mathbf{v_1} = (1, -3, 0) and v2=(1,2,1)\mathbf{v_2} = (-1, 2, 1):

v1×v2=((3)(1)(0)(2),(0)(1)(1)(1),(1)(2)(3)(1))\mathbf{v_1} \times \mathbf{v_2} = \left( (-3)(1) - (0)(2), (0)(-1) - (1)(1), (1)(2) - (-3)(-1) \right)

This simplifies to:

v1×v2=(30,01,23)=(3,1,1)\mathbf{v_1} \times \mathbf{v_2} = \left( -3 - 0, 0 - 1, 2 - 3 \right) = (-3, -1, -1)

Thus, the vector orthogonal to both v1\mathbf{v_1} and v2\mathbf{v_2} is (3,1,1)(-3, -1, -1).

Step 2: Compare this with the given options.

We need to check if any of the provided vectors is a scalar multiple of (3,1,1)(-3, -1, -1).

  • (2,2,6)(2, -2, 6) is not a multiple of (3,1,1)(-3, -1, -1).
  • (3,1,1)(3, 1, 1) is a multiple of (3,1,1)(-3, -1, -1) because (3,1,1)=1×(3,1,1)(3, 1, 1) = -1 \times (-3, -1, -1).

Therefore, (3,1,1)(3, 1, 1) is the vector orthogonal to both v1\mathbf{v_1} and v2\mathbf{v_2}.

Final Answer:

The vector (3,1,1)(3, 1, 1) is orthogonal to both v1\mathbf{v_1} and v2\mathbf{v_2}.

Do you want further details or have any questions?

Here are five related questions to deepen your understanding:

  1. What is the geometric interpretation of the cross product?
  2. How do we find the magnitude of the vector resulting from a cross product?
  3. Can two non-parallel vectors in R3\mathbb{R}^3 have more than one orthogonal vector?
  4. What is the significance of the scalar triple product of three vectors?
  5. How can we use the dot product to verify orthogonality of two vectors?

Tip: The cross product of two vectors gives a vector that is perpendicular to both in 3D space, and its direction is given by the right-hand rule.

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Math Problem Analysis

Mathematical Concepts

Vector Algebra
Cross Product
Orthogonal Vectors

Formulas

Cross product of two vectors v1 × v2 = (v1y * v2z - v1z * v2y, v1z * v2x - v1x * v2z, v1x * v2y - v1y * v2x)

Theorems

Cross Product Theorem for Orthogonal Vectors

Suitable Grade Level

Grades 10-12