find the angle between the given vectors to the nearest tenth of a degree. u= , v= options are 81.6 degrees 25.8 degrees 35.8 degrees 71.6 degrees Thankyou for the help :)

Question

find the angle between the given vectors to the nearest tenth of a degree. u=<8,4> , v=<9,9> options are 81.6 degrees 25.8 degrees 35.8 degrees 71.6 degrees Thankyou for the help :)

anonymous · Answer

Dot product is handy for that.

anonymous · Answer

it is multiple choice

anonymous · Answer

It sure is.

anonymous · Answer

Like CliffSedge said:
$$\frac{ a * b }{ \left| a \right|\left| b \right| } = Cos \theta $$

Where * = dot (dot product)

anonymous · Answer

In your case a<8,4> b<9,9> dot product is : 72 + 36 = 108 magnitude of a : $$\sqrt{8^2 + 4^2}$$ magnitude of b: $$\sqrt{9^2 + 9^2}$$

anonymous · Answer

I'm not getting one of those answer choices..
How about you, @infoshark ?

anonymous · Answer

Flying out to lunch as we speak, will take a peak when I return.  Sorry Cliff.  Girlfriend has me well trained.

anonymous · Answer

Understood.

anonymous · Answer

@cookiemonsta , are you sure those are the correct answers for this?
Did you possibly not copy down the question properly?

anonymous · Answer

I'm getting somewhere around 18 degrees, give or take, how about you @CliffSedge ?

anonymous · Answer

I don't remember, but yeah, it was something like 18.5