could someone maybe help me out and check this?:

use the formula v1xv2=|v1||v2|cos theta to find the cosine of the angle between the vectors v= (-7, 8) and w= (5, 3).

I got -11/63.78------- is that correct or am i way off?

Question

could someone maybe help me out and check this?:

use the formula v1xv2=|v1||v2|cos theta to find the cosine of the angle between the vectors v= (-7, 8) and w= (5, 3). 

I got -11/63.78-------> is that correct or am i way off?

anonymous · Answer

$$v\cdot w=(-7)(5)+(8)(3)=-35+24=-11$$
$$|v|=\sqrt{(-7)^2+8^2}=\sqrt{113}$$
$$|w|=\sqrt{5^2+3^2}=\sqrt{34}$$
$$-11=\sqrt{3842}\cos\theta~~\iff~~\cos\theta\approx-\frac{11}{61.984}~~\iff~~\theta=\cdots$$

anonymous · Answer

would it be .99? @SithsAndGiggles