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Circle Geo (1 Viewer)

withoutaface

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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
 

withoutaface

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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:p
 

Constip8edSkunk

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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

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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

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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

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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 :p
 

jumb

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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.
 

Jase

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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...
 

Grey Council

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

trust me. it's in ssoooooo many.

:-\
 

Archman

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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

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grimreaper said:
I disagree. Mechanics is one of the few obvious "real world" applications of the 4u course
If you want real world applications do general.
 

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