here's another excuse to laugh at a silly girl from laois

LegacyUser

ok here's the problem-im stuck on a maths problem and its ****ing me off,not 'cos im worried about not being able to do my homework but 'cos it is irritating not understanding what a diagonal line is.so here is the question-its form the chapter on combinations by the way:
10 points are chosen on the plane no 3 ot which are collinear.
(i) how many line segments can be drawn using these 10 points?
(ii) hence calculate the number of diagonals in a decagon.
and no i cant ask my teacher to explain 'cos ive tried and she cant do it either and when i thought i had a solution she told me to look up the definition of a diagonal!!!!!!!meanie.
so can someone please take pity on me and tell me how to do part (ii)????please it is irritating.
feel free to make fun of me now
thanx

LegacyUser

There are forty-five unique line segments (taking the ten points as the letters a-j):
[ab][ac][ad][ae][af][ag][ah][ai][aj][bc][bd][be][bf][bg][bh][bi][bj][cd][ce][cf][cg][ch][ci][cj][de][df][dh][di][dj][ef][eg][eh][ei][ej][fg][fh][fi][fj][gh][gi][gj][hi][hj][ij]

There are ten line segments around the outside of the decagon, so subtract ten from forty-five, leaving thirty-five diagonals inside the decagon.

Sorry if this doesn't help.

iMP

LegacyUser

<font face="Verdana, Arial" size="2">Originally posted by imp:
There are ten line segments around the outside of the decagon, so subtract ten from forty-five, leaving thirty-five diagonals inside the decagon.
</font>

Leaving 35 line segments inside the decagon, I would have thought...

Correct me if im wrong, maths isnt my subject.

A

LegacyUser

Oh yea.

Sorry, my brain doesn't function as well with this new maths "teacher" I have.

He says there's nothing better than to do algebra and indices on lonely nights (I kid you not).

iMP

LegacyUser

well i tried that answer but my teacher told me i was wrong and to check the definition of a diagonal cos she said the first and third points were too close to one another to actually make a a,i dunno steep enough slope and that each line had only one diagonal-it doesnt make much sense to me.thanx for trying to help.im just going into panic mode 'cos i just realised that it is only 6 months to my leaving!!!!!!!!!help!!!!

LegacyUser

Is there some sort of diagram to go with this question?? If there is it would be helpful if you could scan it in. But I'll keep thinking and maybe I'll come up with something.

iMP

smiles

<font face="Verdana, Arial" size="2">Originally posted by littlebopeep:
well i tried that answer but my teacher told me i was wrong and to check the definition of a diagonal cos she said the first and third points were too close to one another to actually make a a,i dunno steep enough slope and that each line had only one diagonal-it doesnt make much sense to me.thanx for trying to help.im just going into panic mode 'cos i just realised that it is only 6 months to my leaving!!!!!!!!!help!!!!</font>

doesn't collinear mean that all the points are part of the same line, and so they cant make diagnols unless they are all on one big diagnol line? or if you do curvy lines. they are fun.

love,
me

LegacyUser

Collinear does mean they're on the same line. But it says no 3 points are on the same line, so there's two on each line (at the start and end of the segment), so diagonals can be formed.

iMP

LegacyUser

<font face="Verdana, Arial" size="2">Originally posted by imp:
Is there some sort of diagram to go with this question?? If there is it would be helpful if you could scan it in. But I'll keep thinking and maybe I'll come up with something.

iMP</font>

nope there isnt a diagram-i wrote the full question out for you all.i am able to do part one-the answer is definatly 45,my only real problem is deciding which line segments inside the the decagon are actually diagonals.im feeling like a stupid,dumb moran at present cos school is full of yukky hard things.

LegacyUser

The definition of a diagonal is a line segment joining two non-adjacent vertices of a polygon. The answer for an n-gon is n(n-3)/2 and hence, for a decagon, is 35. Your teacher is a fool.

Marty

LegacyUser

Aha!! Then I am right!! Victory is mine!! Bwahahahahahahah... OK I'll stop now.

iMP

LegacyUser

<font face="Verdana, Arial" size="2">Originally posted by Marty:
The definition of a diagonal is a line segment joining two non-adjacent vertices of a polygon. The answer for an n-gon is n(n-3)/2 and hence, for a decagon, is 35. Your teacher is a fool.

Marty</font>

ok thanx for that,im still a bit confused by the whole thing but ive given up any hope of every understanding maths at this stage.
tata everyone for helping me

LegacyUser

You're from Laois??
Haha!



A

smiles

<font face="Verdana, Arial" size="2">Originally posted by Asuka:
You're from Laois??
Haha!



A</font>

sorry, but stop attaching my friends.

You are from CARRICKMACCROSS!!!!!



lol!

love,
me

LegacyUser

<font face="Verdana, Arial" size="2">Originally posted by Asuka:
You're from Laois??
Haha!



A</font>

you thick stupid moran!!!!!!!!!!!!!!!!!!!!!!!have you only just figured out im from laois????silly child.did you never listen to any of the slagging that i got from numerous people in both sessions or were you too busy doing other things??silly silly silly child

LegacyUser

Too busy doing other things

And im not 'attaching' your friends



A