#vectors

55 messages · Page 1 of 1 (latest)

civic canopy
#

Hi! I need help with b.
Thanks in advance!

IMG_6859.jpg IMG_6860.png
civic wingBOT
#
  1. Do not ping the Moderators, unless someone is breaking the rules.
  2. Do not ping the Helper Moderators, unless there is a conflict between helpers.
  3. Do not ping other members randomly for help.
  4. Ask your question and show the work you've done so far. If you've posted a screenshot of a question, specify which part you need help with.
  5. Wait patiently for a helper to come along.
  6. If the Helper has answered your question, remember to thank them with the Mathematics Ranks bot and close the thread with:

+close
Feel free to nominate the person for helper of the week in #helper-nominations
If you're happy with the help you got here, and the server overall, you can contribute financially as well:

tawdry mountain
#

You took the dot product, right?

#

Hint: Properties of quadrilaterals come into play.

civic canopy
civic canopy
tawdry mountain
tawdry mountain
#

Well, we know BC || AD.

#

So what does that tell us about ABCD?

civic canopy
#

or wait

civic canopy
civic canopy
#

i know that they are parallel but if the length of then aren’t the same then it might not be parallelogram

#

right?

#

or am i wrong

tawdry mountain
civic canopy
#

aaah

#

for part a i got 4

#

so they are equal

#

so now i know that three sides have the length that equals to four which means that the last one would also equal to 4, so DC

#

so it could have been a parallelogram but since all the sides are equal then i would say its a rhombus maybe

#

a parallelogram would have two equal sides and the two other would also equal each other - so for instance 2y sides and 2x sides where the angle is not equal to 90

#

however i am not sure if my conclusion would be correct..

tawdry mountain
civic canopy
tawdry mountain
civic canopy
tawdry mountain
#

And also, consider the angles that a rhombus/parallelogram has.

civic canopy
#

i would say that BA is for instance -vector a

tawdry mountain
#

Yes.

civic canopy
#

-a

#

and BC would be b

#

a*b would equal to -8

#

and so i dont understand why -a*b would equal to 8

tawdry mountain
civic canopy
tawdry mountain
civic canopy
#

i would have just done it like this

civic canopy
#

ohh i drew it incorrectly - i wrote C where i wanted to write D

#

so the calculation doesn’t make any sense

#

now its correct i think

civic canopy
#

alsoo, i need help with g

#

@scenic cliff

normal raptor
# civic canopy Hi! I need help with b. Thanks in advance!

g) $\vec{BP}=\frac12\vec{BD}=\frac12(0\vec{i}-4\sqrt{3}\vec{j})=-2\sqrt{3}\vec{j}$\
since $AC=4\vec{i}$, and we know that $BD$ and $AC$ are perpendicular, we must prove that $k=\frac12$ for $\vec{AP}=k\vec{AC}$\
we can do this with the dot product and thus since $\vec{AC}\cdot\vec{BD}=0$, we have $2\vec{BP}\cdot \frac1k\vec{AP}=0$ and thus $0\times 4-2\sqrt{3}\times 0=0$, so they are indeed perpendicular as well and thus $k=\frac12$

rugged plazaBOT
#

vengeance

1350294910867210291.png
nimble raftBOT
#

@civic canopy

:HelpIcon:| Help Reminder

Hello septembry, this is a friendly reminder that your help request has been inactive for more than 24 hours. If you no longer need assistance, please consider closing the thread using the +close command. This thread will be automatically closed in 3 days if it remains inactive.

civic canopy
#

+close

nimble raftBOT
# civic canopy +close
Please thank your Helpers before closing!

Please thank the helpers who assisted you by clicking the buttons below. You can thank each helper only once. Once you're done, click "Close Post" to close this thread.