Circle Geo D: (2 Viewers)

[kazemagic]

How do u do 2)f im such a noob at circle geo

 

[seanieg89]

HGB=DCB=180-BAD => ABGH concyclic. Try to justify each step yourself.

 

[kazemagic]

O_O yea i got those but how come with only these u can prove HG is concyclic

 

[seanieg89]

All you need is a quadrilateral with a pair of opposite angles supplementary .

 

[kazemagic]

All you need is a quadrilateral with a pair of opposite angles supplementary .

you're referring to quad. HGCD right? so if H and G is cyclic for a pair of points in the circumference, then it means that H and G is always cyclic with any other points in the circumference?

 

[seanieg89]

Nope, no reference to HGCD.

BAD + HGB = 180, so ABGH has a pair of opposite angles which are supplementary. This is one characterisation of cyclic quads.

Not sure what you mean by "H and G is cyclic for a pair of points in the circumference"...

 

[kazemagic]

Nope, no reference to HGCD.

BAD + HGB = 180, so ABGH has a pair of opposite angles which are supplementary. This is one characterisation of cyclic quads.

Not sure what you mean by "H and G is cyclic for a pair of points in the circumference"...

O_O how do u know BAD + HGB = 180

I thought DC was only parallel to HG, so I thought you can't use those alternate angles, complementary angles or co interior angles to find BAD. I have a feeling im doing something really stupid right now =.=

Thanks for ya halp seanie

 

[seanieg89]

BGH=BCD, corresponding angles.

And BCD=180-BAD as we already know that ABCD is cyclic.

 

[kazemagic]

wow im a fking retard yea i get it now thx seanie, i forgot ABCD was cyclic fuk.

 

[seanieg89]

No worries, we all have moments of blindness.

 

[kazemagic]

wat does coincide mean for question b?

 

[Rezen]

That the two points are the same.

 

[kazemagic]

That the two points are the same.

O_O alright thanks, how do i go about proving them lol

 

[Rezen]

Well if cd and dx are parallel and they both intersect at D then they must be the same line.

 

[kazemagic]

Well if cd and dx are parallel and they both intersect at D then they must be the same line.

oh alright thanks! ill think a bit more about it 2morro

 

[kazemagic]

for question b)ii how do u prove whether something is collinear or not? Thanks!

 

[Kurosaki]

Prove angle rap is 180 degrees? That means that points r, a and p are all on the same line since 180 degrees is a straight line. Therefore they are collinear

 

[kazemagic]

Prove angle rap is 180 degrees? That means that points r, a and p are all on the same line since 180 degrees is a straight line. Therefore they are collinear

ohhh alrite thx

 

[Carrotsticks]

To prove that R, A and P are collinear, we must prove that angle RAB + angle BAP = 180, hence RAP is a straight line and therefore R, A and P are collinear.

 

[Kurosaki]

No problem