Question

u = <√7i+√8j>, v = <√8i-√7j>

Answer 1

question?

Answer 2

Find u x v and the angle between u and v to the nearest degree:

Answer 3

your attempt?

Answer 4

none... because the formulas online doesnt fit with my given question...

Answer 5

what is the formula ?

Answer 6

http://www.algebra.com/algebra/homework/Angles.faq.question.620843.html

Answer 7

you mean the formula give you u =< , > and this problem give you u =< +...>
right?

Answer 8

just pick i, k and + out, you have the form of the formula

Answer 9

I mean u =<sqrt7, sqrt8>
v= <sqrt8, -sqrt 7>
problem is solvable

Answer 10

You should do it by yourself. It's not hard. You have formula, just APPLY. Dat sit.
I can give you the answer in 1minute. But I wish you can handle it by YOURSELF

Answer 11

i cant... bcoz im absent in that day... :(

Answer 12

and i dont even know the title of that lesson...

Answer 13

That is an unacceptable reason. You were absent, try to get the knowledge back is your duty.
OK, if you want to study, I can help. If you don't, It's perfectly OK to me.

Answer 14

ok.... just tell me the formula and i will do the rest... and im absent bcoz of measles...

Answer 15

That was the past. Now, you are dealing with the problem you don't know how to solve. Be strong
cos (theta) =

Answer 16

numerator: u dot v
denominator: magnitude of u * magnitude of v
I am sorry for inconvenience, the draw box doesn't work

Answer 17

thanks for encouragement

Answer 18

u dot v = < u1*v1 + u2 *v2>

Answer 19

u =<u1, u2>
v = <v1,v2>
so, u dot v = ???

Answer 20

wait

Answer 21

56i^2-56j^2 ?

Answer 22

take i and j out, nothing to do with them here, you are correct , =??

Answer 23

wait lets try this 1... this is easier
u = < –2, 9 > and v = < 3, –3 >

Answer 24

one more thing , it is sqrt (56) -sqrt(56) =??
not 56 -56

Answer 25

no,no, just continue

Answer 26

a -a =?

Answer 27

0?

Answer 28

you got the answer!!! check the option
u dot v = 0 (one of the option)

Answer 29

yeah the 3rd one ^^ tnx :)

Answer 30

You see!! You CAN do it.

Answer 31

u = < –2, 9 > and v = < 3, –3 > lets try this one :)

Answer 32

ok, as usual, you have 2 parts

Answer 33

cos (theta)=
numerator: u dot v
denominator: magnitude of u * magnitude of v
solve numerator first

Answer 34

uhm... numerator is 33? am i right ?

Answer 35

-33, not 33
be careful with the sign

Answer 36

huh? how come its -? <-2*-3> right ?

Answer 37

no,not yet,
you still have denominator: magnitude of u * magnitude of v
u =<-2,9>
||u|| = sqrt((-2)^2 + 9^2)=?

Answer 38

oh, sorry, your question is about numerator

Answer 39

wait... we're still on numerator...
<-2*-3>+<9*3>

Answer 40

ok, I answer it now
u = <-2 , 9>
v = < 3, -3>
u dot v = < (-2) *3 + 9* (-3)>
= -6 - 27 = -33

Answer 41

u1v1 + u2v2

Answer 42

yeahyeah yeah ^^ my mistake sorry ^^ got confused sorry ^^,

Answer 43

no worry. next the denominator!! I gave you instruction above. DO IT

Answer 44

||u||*||v|| ?

Answer 45

wait... what is the formula for magnitude?

Answer 46

yup

Answer 47

u = 85 v = 0 ?

Answer 48

read my formula above
||u|| = sqrt ((u1)^2 +(u2)^2)

Answer 49

square root, not just that

Answer 50

ooops

Answer 51

square root of (85)

Answer 52

v is not =0, redo

Answer 53

√-2^2+9^2 = √77 ?

Answer 54

\[||u||=\sqrt{(-2)^2 +9^2}=\sqrt{4+81}=\sqrt{85}\]

Answer 55

√3^2+3^2 = 3√2

Answer 56

sqrt85 = 9.21 ?

Answer 57

nope
\[||v||=\sqrt{3^2 + (-3)^2}=\sqrt{9+9}=\sqrt{18}\]

Answer 58

now, put all of them into the formula of cos
\[cos (\theta )= \frac{u\dot v}{||u||*||v||=\frac{-33}{\sqrt{85}*\sqrt{18}}\]
use calculator to find out the answer

Answer 59

-0.84?

Answer 60

yes

Answer 61

again, use calculator to find theta
by hitting cos^- of (-0.84)

Answer 62

shift+cos?

Answer 63

147.14?

Answer 64

2nd + cos

Answer 65

cos^-1(-0.84 = 147.1401196

Answer 66

oh yea, you are right, hehehe

Answer 67

hehehehe :"> tnx ^^youre a great help ^^ :*

Answer 68

ok

Answer 69

^^