Math Is Fun Forum

misheeru

Member

Registered: 2010-02-18

Posts: 4,594

Help With Geometry

Heya

I need some help getting better with geometry! My grade is at stake and i really need to get this stuff so any help is really appreciated! Arigato !

My stuff mainly about circles so they all  have to do with Arc, tangents, diameters, chords etc.

Here are some things im having trouble with:

(they all relate to the picture wich is posted with it)

A-  the common internal tangent is?

B-  the common external tangent is?

C- radius AM is perpendicular to line R, yes or no?

D- is the point of tangency of line S to circle A , the letter M? yes or no?

F- how many possible common tangents to circles A and B can exist?

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Of Moons, Birds and Monsters

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help With Geometry

Hi misheeru;

C) if R is a tangent line at M, then yes R is perpendicular to radius AM

You might find this helpful.

http://www.ies.co.jp/math/java/geo/comtan/comtan.html

F) 3 common tangents can exist

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

misheeru

Member

Registered: 2010-02-18

Posts: 4,594

Re: Help With Geometry

Ok thanks bobbym... the vid on the page is having trouble but I can use the rest to help me.

Ok here the really tough part for me... finding the angles measurement or something rather... anyway I have virtually no clue on these...

theres a few so I'll used the sample questions again.

A-  If m DB = 150 Degrees, then angle A =?

B- If m angle C = 63 degrees, then m angle BDR =?

C- If m angle RDC = 120 degrees, then m DAC =?

Last edited by misheeru (2010-03-12 07:13:03)

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Of Moons, Birds and Monsters

misheeru

Member

Registered: 2010-02-18

Posts: 4,594

Re: Help With Geometry

Hi misheeru;

C) if R is a tangent line at M, then yes R is perpendicular to radius AM

You might find this helpful.

http://www.ies.co.jp/math/java/geo/comtan/comtan.html

F) 3 common tangents can exist

ok so im having trouble telling the difference between the internal and external tangents. What is the diffence and how do you find them?

"the common internal tangent is?"

Ok so since it is on the inside i venture a guess and say the internal is segment AB? (on the first pic)

Last edited by misheeru (2010-03-12 07:36:37)

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Of Moons, Birds and Monsters

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help With Geometry

Hi misheeru;

Nope, R is an internal tangent.

http://jwilson.coe.uga.edu/emt668/EMT66 … teup6.html

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

misheeru

Member

Registered: 2010-02-18

Posts: 4,594

Re: Help With Geometry

Hi misheeru;

Nope, R is an internal tangent.

http://jwilson.coe.uga.edu/emt668/EMT66 … teup6.html

Ok so if the internal is R... then I'm gonna take another guess and say is the external tangent is line S? Maybe?

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Of Moons, Birds and Monsters

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help With Geometry

Hi misheeru;

Yes.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

misheeru

Member

Registered: 2010-02-18

Posts: 4,594

Re: Help With Geometry

sweetness.. ok i think i get the tangent thing a little more. I'll try to answer more of those on my own thanks.

k so wut about the other samples i posted (post 3) ..idk how to find those missing angle-thingy majiggers...

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Of Moons, Birds and Monsters

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Help With Geometry

Hi;

Are those questions straight from the book?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

misheeru

Member

Registered: 2010-02-18

Posts: 4,594

Re: Help With Geometry

no they are samples from a sheet. There is something I left out btw for all on post three: Given:  tangent DE to Circle O.

If that helps, why did i make a mistake?

I need to try and get this stuff, I have a qiuz coming agian (hence the "my grade is at stake?" in post #1)

Last edited by misheeru (2010-03-15 05:54:37)

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Of Moons, Birds and Monsters

misheeru

Member

Registered: 2010-02-18

Posts: 4,594

Re: Help With Geometry

ug why is this so hard for me?? >.<

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Of Moons, Birds and Monsters