Find the angle between the given vectors to the nearest tenth of a degree. u = , v = 20.3° 10.2° 0.2° 30.3°

Question

Find the angle between the given vectors to the nearest tenth of a degree. u = <6, -1>, v = <7, -4> 20.3° 10.2° 0.2° 30.3°

legomyego180 · Answer

cos theta = (vector a dot vector b) / (magnitude of a)(magnitude of b)

laughoutloud · Answer

how do I find the magnitude? @legomyego180

legomyego180 · Answer

$$||u||=\sqrt{6^2+(-1)^2}$$

laughoutloud · Answer

okay I've been trying and trying but I cannot find the answer maybe im  doing the first part wrong? @legomyego180

laughoutloud · Answer

How did you find that? @DallasCowboys88

mathmale · Answer

Let's go with "cos theta = (vector a dot vector b) / (magnitude of a)(magnitude of b)" as posted by legomyego.  Find the magnitudes of vectors u and v, and also find the dot product of those vectors.  Show all work.  If you get these right, we'll move on to finding the cosine of the angle between u and v and then the angle itself.

mathmate · Answer

@laughoutloud
When you cannot find the right answer, the best way to get help is to show what you've done, and the answer you got.
Otherwise you'll get many helpers involved and they still don't know what is causing the error.
If you have the correct answer, but cannot match it, post it as well.  There are times when answers are not correct.

mathmale · Answer

Very well said, mathmate!