need to know how to prove circle geometry proofs? (1 Viewer)

[amime]

as above...

 

[BillyMak]

Probably not. None are really hard to do though, if you know your circle geometry then you should be able to derive any of the basic theorems that we use.

 

[paper cup]

you should be able to they've come up in a few questions...
but they are simple and you should be able to figure it out with a bit of fiddling around if you've studied...

 

[Li0n]

errm, i've never seen proofs for circle geo :S?
most of them were just common sense to me

 

[dawso]

thats the type of question they will hav in 4unit but, adn as people said, they are either common sense or use other circle geo rules

 

[mojako]

thats the type of question they will hav in 4unit but, adn as people said, they are either common sense or use other circle geo rules

dont think so
(about the 4U thing)

 

[dawso]

yes they can, ive seen it in like the '74 paper or somethin (lol, old, but its still there) wat they did was in the first part of the question u had 2 prove that the alt angle theorem, then the rest of it was a normal circle geo question, (harder 3u) i think it was like question 4 or somethin

 

[superbird]

yes they can, ive seen it in like the '74 paper or somethin (lol, old, but its still there) wat they did was in the first part of the question u had 2 prove that the alt angle theorem, then the rest of it was a normal circle geo question, (harder 3u) i think it was like question 4 or somethin

lol yeh thats hell old. the syllabus was changed in the 1980's though so i doubt that question u saw in the 74 paper is still valid

 

[townie]

i'm sure they've asked to prove the tangent-secant rule thingy at some point

 

[Xayma]

They occasionaly ask for a proof of tangents from a common point.

 

[CrashOveride]

in the last 10years, i think only what townie said was tested

 

[utopia_parkway]

if you look in the 3u maths sillybus it has a list of the 17 circle gemoetry properties they can ask you. if you print that of and whenever you can't do a quesiton get it out and go down the list looking for every properties on the list on the circle. after a while you will be able to just go down the list in your head when ever you see a circle geo quesiton.

i also think it says that you don't have to prove the 17 properties that are given on the list. but you might want to check me on that one

 

[Xayma]

Actually it says you must be able to prove:

The perpendicular from the centre of a circle to a chord bisects the chord. Converse.

Equal chords in equal circles are equidistant from the centre. Converse.

Any three non-collinear points lie on a unique circle, whose center is the point of concurrency of the perpendicular bisectors of the intervals joining the points.

Angles in the same segment are equal.

The angle in a semicircle is a right angle.

Opposite angles of a cyclic quadrilateral are supplementary. Converse.

The exterior angle at a vertex of a cyclic quadrilateral equals the interior opposite angle.

If an interval subtends equal angles at two points on the same side of it then the end points of the interval and the two points are concylic.

The angle between a tangent and chord through the point of contact is equal to the angle in the alternate segment.

Tangents to a circle from an external point are equal.

The products of the intercepts of two intersecting chords are equal.

The square of hte length of the tangent from an external point is equal to the product of the intercepts of the secant passing through this point.

When circles touch, the line of centres passes through the point of contact.

 

[utopia_parkway]

my wrong, i better go learn some proofs then

 

[Xayma]

They will often lead you through it.

Eg Tangents to a circle form an external point are equal will have you proving two triangles are congurent. (RHS, radius, angle between tangent and chord, common line from point to centre)