Question

Can anyone help me with 2 trig problem? Is a review question for a test :(

Answer 1

Use the dot product to find the magnitude of u if u=(6,-5)

Answer 2

\[|u| = \sqrt{u*u} = \sqrt{6^2 + (-5)^2}\]

Answer 3

i used the formula and i did not get an answer that match any answer choices.

Answer 4

i dont know what i am doing wrong

Answer 5

36+25 = 61

magnitude is sqrt(61)

Answer 6

oh i got it thank you so much, sorry for troubling you DX

Answer 7

could you help me with another one? please

Answer 8

yw

Answer 9

Find the magnitude and direction angle of v=-2i-6j. Round direction angle to nearest degree.

Answer 10

for this question do you use the same formula like the last question?

Answer 11

yes find magnitude the same way

for angle use
\[\tan \theta = \frac{y}{x}\]
where (x,y) is (-2,-6)

Answer 12

So for the magnitude it would be sqrt 40?

Answer 13

correct, they may want it simplified though
\[\sqrt{40} = 2 \sqrt{10}\]

Answer 14

also for the angle, make sure you are aware which quadrant "v" is in

(-2,-6) is in 3rd quadrant so angle must be between 180 and 270

Answer 15

so would the answer be ||v||= 4 sqrt10 ; theta = 244?

Answer 16

no angle is wrong

Answer 17

uhm because for my answer choice only this choice have the correct magnitude

Answer 18

choices*

Answer 19

use a calculator to find arctan(3) , then add 180 to put it in 3rd quadrant

Answer 20

so theta will be 251

Answer 21

yes well if you round to nearest degree its 252

Answer 22

oh ok, thank you so much for helping me out :D

Answer 23

yw:)