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Does Q6 (a) miss anything? (1 Viewer)

stears

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How did u do the Q6 (a) (i), the question didn't give any angle :confused:
 

withoutaface

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Proof is as follows:

ABD=ACD(angles subtended from the same chord)
:. FBD=FCA (angles on a straight line are supplementary)
But FBD+FCA=180 (opposite angles of a cyclic quad are supplementary)
:. FDB=180/2=90
 

skypryn

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in those types of q's you have to be smart....it is normally 90, 180, 60 etc cos you can cancel <'s
 

absolution*

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I got those answers but didnt gave a really retarded proof coz i knew by looking at it it was a right angle.
Then i just wrote that the line was = 2r. pure guess. I hope i get marks.
 

mazza_728

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I didnt get the first part at all.. didnt have time to figure it all out but i guessed the 2nd part to be 2r do u think ill still get it???
 

CharlieB

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the question was pretty straightforward...

they told you the other quad was cyclic so it obviouslt involved the exterior angle thing
 

dawso

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yeah, this question was actually heaps easy, if u got the question rite....

(dumbass me first didnt read the question 2 see wat was given as the cyclic quadrilateral and i was workin out the value of the wrong angle)

so theres a tip peoples, read the question!!!!
 

mr phil

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yea i fudged that question aswell.. shouldve read the whole thing.. coz i assumed the cyclic quad was the one in the diagram, (the one with a circle around it!)
i said let sum angle = a, let the other one = b, so whatevvr angle = a +b
any chance at one out of the 2 marks?!

second part AD = rM, where M is a variable ? doubt that'd get the one mark
 

Li0n

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lol dude i did everything in algebra.
i didnt know you could assume that AD was diameter. for ii i go
Construct DX such that DX is a diameter of the circle
then i go DX = (2r)<sup>2</sup> = pythagoras bla.
 

bevstarrunner

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you can say that AD is the diameter when you prove either < ABD or < ACD to be 90º. Then you can say it is diameter because AD subtends the right angle at the circumference.
 

beverly

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argh..i knew i shouldve guessed it. i came out of the exam thinking..i shouldve just guessed 90 and 2r cos' that's the only logical answer
 

KeypadSDM

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It's a 1 marker, for the length of the line to be a simple function of r, the angle must be 90 degrees. Man, answer by inspection is so so much easier than actually doing anything.
 

Komaticom

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Damn diagram, so misleading. They drew angles so wrong. How can two opposite angles of a cyclic quad add to equal 180 when they're drawn to be both obtuse... *grumble grumble * "not to scale" *grumble grumble*
 

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