# Circle Geo (1 Viewer)

#### withoutaface

This is from a Riverview trial, I got the rest of the test out but couldn't manage part iii of this circle geometry question out. Any help would be appreciated.
Thanks,
Justin

#### ngai

##### Member
FIVE marks?
theyre so generous

#### withoutaface

ngai said:
FIVE marks?
theyre so generous
Well the other part of question 8 was worth 8 marks and it was an absolute joke in how easy it was

#### Constip8edSkunk

##### Joga Bonito
ECD = EFD (ECFD a cyclic quad)
ECD = ABD (ABCD cyclic quad)
so ABD = EFD

ABD + GDB + DGB = pi (triangle angle sum)
Now GDB = GFB, DGB =DFB (alt.angles)
so EFD + GFB + DFB =EFG = pi
.'. E, F, G, colliniear

#### withoutaface

Constip8edSkunk said:
ECD = EFD (ECFD a cyclic quad)
ECD = ABD (ABCD cyclic quad)
so ABD = EFD

ABD + GDB + DGB = pi (triangle angle sum)
Now GDB = GFB, DGB =DFB (alt.angles)
so EFD + GFB + DFB =EFG = pi
.'. E, F, G, colliniear
Thanks

#### dawso

##### needmorecustomstatusspace
yeah, i cant beleive that that was worth 5 marks, but then again, in our trial, we got 1 mark in the circle geometry bit just copying the diagram, and some people didnt even pik up that easy mark, oh well, their fault
-dawso

#### CrashOveride

##### Active Member
I concur with the previous post. Can you imagine, a mark for "copy or trace this diagram into your writing booklet". Come on, general don't have it so easy in comparison

#### jumb

##### mr jumb
dawso said:
yeah, i cant beleive that that was worth 5 marks, but then again, in our trial, we got 1 mark in the circle geometry bit just copying the diagram, and some people didnt even pik up that easy mark, oh well, their fault
-dawso
Usually they integrate it into an easy question for 1 mark. eg copy the diagram and explain why x = y.

#### gordo

##### Resident Jew
circle geometry is so stupid
wen would it ever be needed

#### CrashOveride

##### Active Member
When working with circles of course

#### Jase

##### Member
Suppose an evil dictator like neo-hitler-jesus appears and he is calling upon the world heroes to prove to him that the second tangent to three external points from a large circle is concurrent to the centre of three circles each with their centres on the tangents arbitrarily. And if you win he will promise to commit suicide and the world will be saved.

So think again before taking circle geo for granted, We could be heroes...

#### jumb

##### mr jumb
Haha. I feel special now.

#### spice girl

##### magic mirror
i think this question was from the 2002 HSC (Q4?).

simson's line.

#### Grey Council

##### Legend
I've seen this question in more trials papers than ANY other circle geo question.

trust me. it's in ssoooooo many.

:-\

#### Archman

##### Member
gordo said:
circle geometry is so stupid
wen would it ever be needed
haha well do you want to get rid of one of the few last topics in hsc maths that is non mechanical and requires some sort of deductive reasoning?

#### withoutaface

I want conics to go. Fucking algebra bashing.

#### Archman

##### Member
i agree. to some extent, mechanics too.

#### grimreaper

##### Member
Archman said:
i agree. to some extent, mechanics too.
I disagree. Mechanics is one of the few obvious "real world" applications of the 4u course

#### CrashOveride

##### Active Member
I would agree with the above post.