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Let alpha, beta, gamma are distinct real...

Let `alpha, beta, gamma` are distinct real numbers. The points with position vectors ` alpha i + beta j + gamma k`, `beta i + gamma j + alpha k`, `gamma i + alpha j + beta k`

A

are collinear

B

form an equilateral triangle

C

form a scalene triangle

D

form a right angled triangle

Text Solution

Verified by Experts

Let given point be A, B and C with positive vectors `alphahati+betahatj+gammahatk,betahati+gammahatj+alphahatk and gamma hati+alphahatj+betahatk`
As `alpha,beta and gamma` are distinct real numbers, therefore ABC form a triangle.
Clearly, `AB=OB-OA=(betahati+gammahatj+alphahatk)-(alphahati+betahatj+gammahatk)`
`=(beta-alpha)hati+(gamma-beta)hatj+(alpha-gamma)hatk`

Now, `|AB|=sqrt((beta-alpha)^(2)+(gamma-beta)^(2)+(alpha-gamma)^(2))`
Similarly, `BC=CA=sqrt((beta-alpha)^(2)+(gamma-beta)^(2)+(alpha-gamma)^(2))`
`thereforeDeltaABC` is an equilateral triangle.
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