Angle Between Two Vectors
The angle between two vectors
and
is given by the formula:

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Examples
Calculate the dot product and the angle formed by the following vectors:
1.
= (3, 4) and
= (−8, 6)
·
= 3 · (−8) + 4 · 6 = 0

2.
= (5, 6) and
= (−1, 4)
·
= 5 · (−1) + 6 · 4 = 19

3.
= (3, 5) and
= (−1, 6)
·
= 3 · (−1) + 5 · 6 = 27

Given the vectors
= (2, k) and
= (3, −2), calculate the value of k so that the vectors
and
are:
1 Perpendicular.
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2 Parallel.
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3 Make an angle of 60°.
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Find the value of k if the angle between
= (3, k) and
= (2, −1) is:
1 90°
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2 0°
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3 45°
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Calculate the angles of the triangle with vertices: A = (6,0), B = (3,5) and C = (−1,−1).
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