qu = (0.0, 1)T and ru = (0.5, 0.866)T ?
Answer:
qu · ru = cos θ = 0.866. So θ = arc cos 0.866 = 30°.
qu = (0.0, 1)T and ru = (0.5, 0.866)T ?
qu · ru = cos θ = 0.866. So θ = arc cos 0.866 = 30°.
The picture shows qu and ru and the angle between them.
Since qu · ru = ru · qu , the angle is the angle (< 180°) between the two vectors. It does not matter which vector is first in the dot product.
Sometimes (especially when vectors point into diferent quadrants) it really helps to draw a picture to check that your answer makes sense.
What is the cosine of the angle between the two unit vectors
represented by