Angle between line vector r = (2i - j + k) + λ(-i + j + k)

Question

Angle between line \(\vec{r} = (2\hat{i} - \hat{j} + \hat{k}) + \lambda(-\hat{i} + \hat{j} + \hat{k})\) and plane \(\vec{r} = (3\hat{i} + 2\hat{j} - \hat{k}) = 4: \)

(a) sin^-1(-2/√42)

(b) sin^-1(2/√42)

(c) cos^-1(-2/√42)

(d) cos^-1(2/√42)

Answer 1

Answer is (a)

We know that angle between two lines