Maths · Scalar and vector products

Let be distinct real numbers. The points with position vectors ai

Let \( a, \beta, \gamma \) be distinct real numbers. The points with position vectors ai \( +\beta j+ \) \( \gamma k, \beta i+\gamma j+a k, \gamma i+a j+\beta k \)

  • A. are collinear
  • B. form an equilateral triangle
  • C. form an scalene triangle
  • D. form a right angled triangle

Step-by-step solution

Let points P, Q, R have position vectors v1, v2, v3. Compute vectors PQ = v2 - v1, PR = v3 - v1, QR = v3 - v2. Their components are cyclic permutations of (β-α, γ-β, α-γ). The squared magnitudes are equal because they are sums of squares of the same three differences in different orders. Hence all sides are equal, so triangle is equilateral.
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