Circle Geometry (1 Viewer)

[RideTheLightnin]

Hey guys, I understand that the BOS are a bit iffy on what they classify as real theorems and proofs for their answers, and I was wondering if they have a list of real acceptable proofs, or something along those lines that are recommended. At the moment im doing some exercises and the answers don't include the reasons, so just seeing if there are any specific ones set by the BOS (cos they complain about shitty ones in the notes from the marking centre).

Cheers guys.

 

[fishy89sg]

http://www.boardofstudies.nsw.edu.au/syllabus_hsc/pdf_doc/maths23u_syl.pdf

pages 28-31

i think thats what you want

 

[RideTheLightnin]

thanks champ

 

[RideTheLightnin]

just not too sure how to do this question...didnt think it required a new thread
its in fitzy, page 12, q 10

thanks guys

 

[fishy89sg]

omg i remember that question and we could not do it at school

its not concyclic or anything

 

[zeek]

the answer says 109 but i get 60...

 

[RideTheLightnin]

i just cant get it lol

 

[Ennaybur]

i get 60 aswell :S

 

[zeek]

just forget about it for now and move onto other stuff. Usualy the HSC exam has only one circle geometry question anyways.

EDIT: maybe someone else can get it from what im thinking

1. You can prove that there is a cyclic quad. if you construct an angle at the opposite side to the centre O

 

[Riviet]

I got 109.

You have to make several constructions, prove two triangles are congruent, use angle in a semi-circle = 90^o, angle sum of triangle, and angle at centre theorem to find x.

I'll see if I can scan in a diagram labelling all this info.

 

[zeek]

ewwwwwwwwwwwwwwwwwww wat a dirty question man
dw RideTheLightnin, i don't think they'll have stuff like that in this years HSC

 

[Riviet]

 

[fishy89sg]

ive never seen a 'find the value of x' question in the hsc (x = 180- A, x=90, x=180 dont count lol)

 

[SoulSearcher]

But theorectically it could pop up in an HSC exam, so still better prepared