Find the area of the triangle formed by the points A(1, 2, 3), B(4, 5, 6), and C

Practice Questions

Q1
Find the area of the triangle formed by the points A(1, 2, 3), B(4, 5, 6), and C(7, 8, 9) using the vector product.
  1. 0
  2. 1
  3. 2
  4. 3

Questions & Step-by-Step Solutions

Find the area of the triangle formed by the points A(1, 2, 3), B(4, 5, 6), and C(7, 8, 9) using the vector product.
Correct Answer: 0
  • Step 1: Identify the points A, B, and C in 3D space. A(1, 2, 3), B(4, 5, 6), C(7, 8, 9).
  • Step 2: Calculate the vectors AB and AC. AB = B - A = (4-1, 5-2, 6-3) = (3, 3, 3). AC = C - A = (7-1, 8-2, 9-3) = (6, 6, 6).
  • Step 3: Use the cross product to find AB × AC. The formula for the cross product in 3D is given by the determinant of a matrix formed by the unit vectors i, j, k and the components of AB and AC.
  • Step 4: Set up the determinant: |i j k| |3 3 3| |6 6 6|.
  • Step 5: Calculate the determinant. Since AB and AC are parallel (both are multiples of each other), the cross product will be zero.
  • Step 6: Find the magnitude of the cross product |AB × AC|, which is 0.
  • Step 7: Calculate the area of the triangle using the formula Area = 0.5 * |AB × AC|. Since |AB × AC| is 0, the area is 0.
  • Step 8: Conclude that the area of the triangle is 0 because the points A, B, and C are collinear.
  • Vector Product – The vector product (cross product) of two vectors gives a vector perpendicular to the plane formed by the two vectors, and its magnitude represents the area of the parallelogram formed by those vectors.
  • Collinearity – Three points are collinear if they lie on the same straight line, which results in an area of zero for the triangle formed by them.
  • Area of a Triangle – The area of a triangle can be calculated using the formula Area = 0.5 * |AB × AC|, where AB and AC are vectors from one vertex to the other two vertices.
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