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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Specialist Mathematics => Topic started by: dekoyl on December 19, 2008, 09:42:47 pm

Title: Adding extra points
Post by: dekoyl on December 19, 2008, 09:42:47 pm: For a vectors question, it is based off a cuboid with corners A,B,C,D,E,F,G.

Point M is midpoint of ED.

For a question where it wants me to find $\vec{OM}$ , I introduced a point 'N', which is directly under point M (i.e. it is the midpoint of DC). I got the answer right.

Is this allowed? Can I just add a point N without the question mentioning N? (Or was N unnecessary?)

Thankee :)
Title: Re: Adding extra points
Post by: Mao on December 19, 2008, 09:51:42 pm: i don't see why not, but it's unecessary.
Title: Re: Adding extra points
Post by: dekoyl on December 19, 2008, 09:55:56 pm: Unnecessary you say? :(

This is what I did.
(http://i42.tinypic.com/35hjk88.png)

I'm trying to get rid of the superfluous steps.
Title: Re: Adding extra points
Post by: /0 on December 19, 2008, 10:23:56 pm: Don't get it, wouldn't that take the same amount of steps?

$OM = OC + CN + NM = OC + CD + DM$ ?
Title: Re: Adding extra points
Post by: dekoyl on December 19, 2008, 10:28:05 pm: Oh crap, this isn't good.
I think I'm getting the key concepts screwed up. :(

I did:
OM = ON + OG

ON = c + $\frac1{2}$ a

OM = c + $\frac1{2}$ a + g

:( **** .
Title: Re: Adding extra points
Post by: /0 on December 19, 2008, 10:31:02 pm: As far as I know that seems to be right :)
You just compressed 2 steps into 1 when finding ON, but hey, whatever floats your boat.
Title: Re: Adding extra points
Post by: orsel on December 20, 2008, 12:10:26 am: As long as you define it clearly.