drawing a blank (1 Viewer)

[Lainee]

Originally posted by Lainee
ACDE shows a rhombus if AE and DC are parallel.

Ahhhh.. it seems like I answered my own concern. It's not even a *rhombus*, nor a parallelogram it's a trapezium! :rofl: Thus my assumption doesn't work. Oh I should to go back to yr4 and relearn my shapes, I think.

Editted: Because I still don't know my shapes. >.<

 

[ND]

Yeh sorry it can be drawn without the intersection of AC and DE.

 

[Lainee]

Originally posted by fashionista
yes i did...fitzpatrick 3u one... on my diagram..which i tried to post ACDE makes a trapezium and AC does by no means intersect DE. does any one noe how to post a piccie??

*checks her copy of Flitz* There's a diagram!!! *kills herself* How was I suppose to know where B was, yeesh. It could have been on the circle (as was how I drew it) too!

 

[ND]

Originally posted by Lainee
*checks her copy of Flitz* There's a diagram!!! *kills herself* How was I suppose to know where B was, yeesh. It could have been on the circle (as was how I drew it) too!

B has to be on the circle; the say "chord BE".

 

[Lainee]

The moral of this question is: you should always provide a diagram if possible in geometry questions.

 

[ND]

It should work either way (with or without the intersection of AC and DE).

 

[Lainee]

Hastily drawn diagram in Paint (can you tell? ) Duplicated from the textbook.

 

[ND]

Hey that's way better than my mspaint diagrams... But are you sure that that diagram corresponds with that question? Cos otherwise Fitz has fucked up bad.

edit: i mean, you can't exactly prove that two lines a parallel when they intersect (as in the diagram).

 

[Lainee]

No.. no.. i'm not sure that it does. Alright, I'm feeling more and more stupid by the post. *sniffs* Deceptive placement of diagrams... blah.

 

[ND]

Heheheh.

 

[Xayma]

Umm where is the chord AC, did you mean BC? Your diagrams wrong somewhere, cause theres no way AE is parallel to CD

 

[fashionista]

Lainee! i did that too but guess wut i found out? thats the diagram to question 28. how did u attach tha picha tho? cuz if u tell then i can show u the diagram.

 

[KeypadSDM]

< BED + < ADE = 180*
Note: < BEA = < ADC (Angles subtended by equal chords in the same arc)
:. < BED - < BEA + < EDA + < ADC = 180*
:. < AED + < EDC = 180*
:. AE || CD (Co-interior angles supplementary)

 

[fashionista]

yay!! thank u KeypadSDM!!....thank u everee one!!!

 

[KeypadSDM]

Not a problemo

 

[ND]

Nice.

 

[fashionista]

oooh.sorry to bother u all gain but i gots this last kwestion which is kinda mind boggling(jus to me..mayb not to evereeone else):

35. Two perpendicular chords AB and CD, centre O, intersect at E. Prove that <AOD+<BOC=180 degrees

can sum1 pleese help me?????

 

[fashionista]

i tried to drawa picture but im not sure how correct i was as the book did not provide one how sad.

 

[Xayma]

Originally posted by fashionista
oooh.sorry to bother u all gain but i gots this last kwestion which is kinda mind boggling(jus to me..mayb not to evereeone else):

35. Two perpendicular chords AB and CD, centre O, intersect at E. Prove that <AOD+<BOC=180 degrees

can sum1 pleese help me?????

ok first of all put a space between the angle brackets as they arent showing up because it thinks its HTML, I had to get the quick quote to show it.

 

[ND]

Let /_ACO=b, /_BAC=a
/_BOC=2a (angle subtended is centre is twice angle subtended at circumference)
/_AOD=2b (as above)
also a+b+90*=180* (angle sum of /\CAE=180*)
.'. a+b=90
/_BOC+/_AOD=2a+2b=180*

edit: i should probably put in the question:

35. Two perpendicular chords AB and CD, centre O, intersect at E. Prove that <AOD+<BOC=180 degrees

edit2: damn didn't work, oh well, quote to see the question.