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The angle between two vectors aa→ and bb→ with magnitudes 3 and 4, respectively, and aba→⋅b→=23 is ______. - Mathematics

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Question

The angle between two vectors `vec"a"` and `vec"b"` with magnitudes `sqrt(3)` and 4, respectively, and `vec"a" * vec"b" = 2sqrt(3)` is ______.

Options

  • `pi/6`

  • `pi/3`

  • `pi/2`

  • `(5pi)/2`

MCQ
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Solution

The angle between two vectors `vec"a"` and `vec"b"` with magnitudes `sqrt(3)` and 4, respectively, and `vec"a" * vec"b" = 2sqrt(3)` is `pi/3`.

Explanation:

Here, given that `|vec"a"| = sqrt(3)`

`|vec"b"|` = 4

And `vec"a" * vec"b" = 2sqrt(3)`

∴ From scalar product, we know that

`vec"a" * vec"b" = |vec"a"||vec"b"| cos theta`

⇒ `2sqrt(3) = sqrt(3) * 4 cos theta`

⇒ `cos theta = (2sqrt(3))/(sqrt(3) * 4) = 1/2`

∴  `theta = pi/3`

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Chapter 10: Vector Algebra - Exercise [Page 217]

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NCERT Exemplar Mathematics [English] Class 12
Chapter 10 Vector Algebra
Exercise | Q 22 | Page 217

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