Math Problem Statement

The following three points lie on a straight line: A(-4,-1,6), B(3,5,0), C(-5,-5,-5)

Solution

To check if the points A(4,1,6)A(-4, -1, 6), B(3,5,0)B(3, 5, 0), and C(5,5,5)C(-5, -5, -5) lie on a straight line, we need to verify if they are collinear. One method is to calculate the vectors AB\overrightarrow{AB} and AC\overrightarrow{AC} and see if they are scalar multiples of each other, which would indicate that the points are collinear.

Step 1: Calculate the vector AB\overrightarrow{AB}

AB=BA=(3(4),5(1),06)=(3+4,5+1,06)=(7,6,6)\overrightarrow{AB} = B - A = (3 - (-4), 5 - (-1), 0 - 6) = (3 + 4, 5 + 1, 0 - 6) = (7, 6, -6)

Step 2: Calculate the vector AC\overrightarrow{AC}

AC=CA=(5(4),5(1),56)=(5+4,5+1,56)=(1,4,11)\overrightarrow{AC} = C - A = (-5 - (-4), -5 - (-1), -5 - 6) = (-5 + 4, -5 + 1, -5 - 6) = (-1, -4, -11)

Step 3: Check if AB\overrightarrow{AB} and AC\overrightarrow{AC} are scalar multiples

We need to check if there exists a scalar kk such that: (7,6,6)=k(1,4,11)(7, 6, -6) = k(-1, -4, -11)

Comparing the components:

  1. 7=k(1)    k=77 = k(-1) \implies k = -7
  2. 6=k(4)    k=64=326 = k(-4) \implies k = -\frac{6}{4} = -\frac{3}{2}
  3. 6=k(11)    k=611-6 = k(-11) \implies k = \frac{6}{11}

Since kk is not consistent across all three components, the vectors are not scalar multiples, meaning that the points AA, BB, and CC are not collinear and do not lie on a straight line.

Let me know if you'd like more details or have questions!

Here are five related questions:

  1. How can you find the distance between two points in 3D space?
  2. What is the equation of a line in 3D given two points?
  3. How do you determine if vectors are parallel?
  4. Can you find the area of a triangle formed by three points in 3D space?
  5. How do you calculate the cross product of two vectors?

Tip: In 3D geometry, using the cross product of vectors is a great way to check if points are collinear, as collinear vectors will have a zero cross product.

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Math Problem Analysis

Mathematical Concepts

Vectors
Collinearity in 3D Geometry
Scalar Multiples

Formulas

Vector subtraction: \overrightarrow{AB} = B - A
Collinearity check: checking if vectors are scalar multiples

Theorems

Vectors are collinear if they are scalar multiples of each other.

Suitable Grade Level

Grades 10-12