Find the angle between the following pairs of lines.
(i) `hatr = 2hati-5hatj+hatk+lambda(3hati+2hatj+6hatk)` and `vecr = 7 hati-6hatk+mu(hati+2hatj+2hatk)`
(ii) `vecr = 3hati+hatj-2hatk+lambda(hati-hatj-2hatk)` and
`vecr= 2hati-hatj-56hatk+mu(3hati-5hatj-4hatk)`

Explanation

To find the angle between the given pairs of lines, we will use the formula for the cosine of the angle between two vectors. The angle \( \theta \) between two vectors \( \mathbf{b_1} \) and \( \mathbf{b_2} \) is given by:

\[ \cos \theta = \frac{\mathbf{b_1} \cdot \mathbf{b_2}}{|\mathbf{b_1}| |\mathbf{b_2}|} \]

### Part (i)

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