Question

Please help:
Find the angle between the given vectors to the nearest tenth of a degree.

u = <2, -4>, v = <3, -8>

3.0°

6.0°

-7.0°

16.0°

Answer 1

u.v
arccos ( ----------- )
sqrt(u.u * v.v)

Answer 2

doesnt that make arccos of 1?

Answer 3

since the sqrt will take off the squared? making the top equal to the bottom

Answer 4

the sqrt doesnt take off the dot products ...

Answer 5

u = <2, -4>
u = <2, -4>
-----------
dot: 4 + 16 = 20



v = <3, -8>
v = <3, -8>
-----------
dot: 9 + 64 = 73

the sqrt(20*73) is not equal to 20*73

Answer 6

u = <2, -4>
v = <3, -8>
------------
dot: 6 + 32 = 40

Answer 7

well, 6+32 = 38