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The angle between the vectors 3i+j+2k and 2i-2j+4k is
  • a)
    cos⁻1(2/√7)
  • b)
    sin⁻1(2/√7)
  • c)
    cos⁻1(2/√5)
  • d)
    sin⁻1(1/√7)
Correct answer is option 'B'. Can you explain this answer?
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The angle between the vectors 3i+j+2k and 2i-2j+4k isa)cos⁻1(2/&...
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The angle between the vectors 3i+j+2k and 2i-2j+4k isa)cos⁻1(2/&...
To find the angle between two vectors, we use the formula:

cosθ = (a · b) / (|a| |b|)

where a and b are the two vectors, · represents the dot product, and |a| and |b| represent the magnitudes of the vectors.

Using this formula, we have:

a = 3i + j + 2k
b = 2i - 2j + 4k

a · b = (3i + j + 2k) · (2i - 2j + 4k)
= 6i^2 - 6j^2 + 8k^2
= 6(1) - 6(1) + 8(1)
= 8

|a| = sqrt(3^2 + 1^2 + 2^2) = sqrt(14)
|b| = sqrt(2^2 + (-2)^2 + 4^2) = sqrt(24)

Substituting into the formula, we get:

cosθ = (a · b) / (|a| |b|)
= 8 / (sqrt(14) sqrt(24))
= 2 / sqrt(21)

Therefore, the angle between the vectors is:

θ = cos^-1(2 / sqrt(21)) ≈ 36.87 degrees (rounded to two decimal places)
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The angle between the vectors 3i+j+2k and 2i-2j+4k isa)cos⁻1(2/&...
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The angle between the vectors 3i+j+2k and 2i-2j+4k isa)cos⁻1(2/√7)b)sin⁻1(2/√7)c)cos⁻1(2/√5)d)sin⁻1(1/√7)Correct answer is option 'B'. Can you explain this answer?
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