Question

Help with angles between vector.

Answer 1

Find the angle θ between the vectors v = -5i + 6j and w = 5i − j. Round your answer to the nearest hundredth of a degree.

Answer 2

sqrt((-5)^2 + (6)^2)=sqrt61

sqrt((5)^2 + (-1)^2)=sqrt26

(-5*5)+(6*-1)=-10+(-6)=4

cos^1(4/sqrt61sqrt26)=84.24 degrees

Answer 3

@freckles does my work look correct?

Answer 4

one sec while I look

Answer 5

oh no

Answer 6

I know you know this but what is -5*5 again?

Answer 7

oh crap -25

Answer 8

rip

Answer 9

so -25+(-6)=-31

Answer 10

and I hate to be that person but -10-6=-16 (which still isn't the correct dot product of the two vectors :p)

Answer 11

I know I messed up hard loool

Answer 12

just saw it before you said it

Answer 13

would -31 be correct for v*w?

Answer 14

yep yep

Answer 15

so you have to redo trying to find the angle between

Answer 16

cos^-1(-31/sqrt61sqrt26)=141.11

Answer 17

141.12*

Answer 18

which looks about correct
so we that A+90+B should probably be between 180 and 90 deg
:)