Question

Find the angle between v and w. Round your answer to one decimal place, if necessary.
v = -5i + 7j, w = -6i - 4j

Answer 1

that's what i have so far

Answer 2

@amistre64

Answer 3

4^2 is not 24

Answer 4

wow. catch 1!

Answer 5

the rest is good

Answer 6

alright
so 52 instead

Answer 7

\[\sqrt{52}\]

Answer 8

to save some wear and tear, (-5)^2 = (5)^2 so the signs arent that relevant to the length

Answer 9

true, got it.

Answer 10

and i like to stack the vectors that way the parts dont get 'confused' in the dot

ai + bj
xi + yj
------
ax + by

Answer 11

you did fine other than 4^2 tho

Answer 12

but to figure out the angle i would simplify the \[\theta = \cos^{-1} \frac{ 2 }{ \sqrt{74}\sqrt{52}}\]

Answer 13

just stick it in the calculator ... no need to try to reduce and whatnot

Answer 14

that gives me: http://www.wolframalpha.com/input/?i=cos%5E-1%282%2F%28sqrt%2874%29*sqrt%2860%29%29%29

Answer 15

mkae sure your in degree mode if you want degrees

Answer 16

sigh, its not 60

Answer 17

god damnit http://www.wolframalpha.com/input/?i=cos%5E-1%282%2F%28sqrt%2874%29*sqrt%2852%29%29%29

Answer 18

6^2 + 4^2 is not going to be 60

Answer 19

so 88.15 degrees

Answer 20

correct

Answer 21

i had that in another tab before you corrected me the first time

Answer 22

I swear i make more tiny mistakes than anything else.

Answer 23

thank you again!

Answer 24

the simple things really get you in the end :) i told my calculus teacher ... do you know how much algebra i had to forget for this test?

Answer 25

LOL

Answer 26

It even rings completely true!

Answer 27

:) good luck