Question

Please help! I'll give a medal.
Let vec a = -4 i-2 j+1 k and vec b = 0 i-5 j+5 k.
Find the angle between the vectors

Answer 1

dot product a . b = |a| |b| cos theta

Answer 2

theta is the angle between these 2 vectors

Answer 3

So it would be cos theta=\[\frac{ 15 }{ \sqrt{21}\sqrt{50} }\] which results in theta being about 62.42?

Answer 4

yes