# Mathamania discussion

geometry

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Okay, I'm going to give it a try. Not promising it will make sense... =D

If a line divides two sides of a triangle

proportionally, then it is parallel to the third side.

In order for a line to divide two sides a triangle proportionally, it must create two overlapped similar triangles. For the triangles to be similar (proportional) they're angles must be equal. If all the angles are equal then the line

For example: In order to divide a right triangle proportionally, the line must create another 90 degree angle (along with the other angles). The only way to get a 90 degree angle is to have a straight line intersect a straight line. The intersecting straight line then, must be parallel to one or the other straight lines of the right triangle.

**Converse of the Triangle Proportionality Theorem:**If a line divides two sides of a triangle

proportionally, then it is parallel to the third side.

**Proof:**In order for a line to divide two sides a triangle proportionally, it must create two overlapped similar triangles. For the triangles to be similar (proportional) they're angles must be equal. If all the angles are equal then the line

**must**be parallel to the third side of the triangle.For example: In order to divide a right triangle proportionally, the line must create another 90 degree angle (along with the other angles). The only way to get a 90 degree angle is to have a straight line intersect a straight line. The intersecting straight line then, must be parallel to one or the other straight lines of the right triangle.

Your explanation was perfect. Oh, and to answer your question, we are going to have fun doing super hard problems.

Yay! Thanks Joon! =D

Yes, we are going to have so much fun doing really hard problems! I thrive on puzzles! The only bad part is that, when faced with a puzzle/problem, it sort of takes over my brain (or is, at least, annoyingly naggy) until I know the answer. :)

Yes, we are going to have so much fun doing really hard problems! I thrive on puzzles! The only bad part is that, when faced with a puzzle/problem, it sort of takes over my brain (or is, at least, annoyingly naggy) until I know the answer. :)

Alright, here's another one:

The radius of the circle is 12cm. There is an angle like this < (angle ABC) in the circle, but it does NOT pass through the center of the circle and who's inner angle is 40 degrees. Find the length of arc ABC. Round the answer to the nearest hundredth. (Again, this would be much easier if I was able to post a diagram.)

The radius of the circle is 12cm. There is an angle like this < (angle ABC) in the circle, but it does NOT pass through the center of the circle and who's inner angle is 40 degrees. Find the length of arc ABC. Round the answer to the nearest hundredth. (Again, this would be much easier if I was able to post a diagram.)

Elaine, what grade are you in? and what mathe course do you take in school?

yejin--how was spicewood?

yejin--how was spicewood?

Not all people like to tell information. Some people like to stay reserved. Oh, and I thought that the Spicewood thing was okay. I had to play Pink Panther about 25 times.

me, too. The songs and i memorized every single word we said even other people's words in woodwind quintet.

Yep.

Definition for Geometry:

the branch of mathematics dealing with the properties, measurements, and relationships of points, lines, planes, and solids.

Sorry, I was curious. =)

Definition for Geometry:

the branch of mathematics dealing with the properties, measurements, and relationships of points, lines, planes, and solids.

Sorry, I was curious. =)

Yeah, most of it deals with shapes, lines, degress, etc. It is not easy if you are not a good visualizer. (Like me.)

We have different sections. This section i'm doing now has algebra, quadratic graphs, Surds, and some more stuff. Do you do GCSEs?

surds are like

√20 is a surd because the number is not whole.

but say √8 simplified is √4 x √2 which is written like this: 2√2

It's hard to explain on a computer.

√20 is a surd because the number is not whole.

but say √8 simplified is √4 x √2 which is written like this: 2√2

It's hard to explain on a computer.

Yeah! And you like add, divide, subtract-ect them.

But for my non-calculator exam I had to find √20

I was like huh??

But for my non-calculator exam I had to find √20

I was like huh??

*Elaine wrote: "Alright, here's another one:*

The radius of the circle is 12cm. There is an angle like this < (angle ABC) in the circle, but it does NOT pass through the center of the circle and who's inner angle is 40 degrees. Find the length of arc ABC. Round the answer to the nearest hundredth. (Again, this would be much easier if I was able to post a diagram.)

The radius of the circle is 12cm. There is an angle like this < (angle ABC) in the circle, but it does NOT pass through the center of the circle and who's inner angle is 40 degrees. Find the length of arc ABC. Round the answer to the nearest hundredth. (Again, this would be much easier if I was able to post a diagram.)

No one has answered my question yet!!!

*Elaine wrote: "Elaine wrote: "Alright, here's another one:*

The radius of the circle is 12cm. There is an angle like this

No one has answered my question yet!!!

"

The radius of the circle is 12cm. There is an angle like this

No one has answered my question yet!!!

"

i agree with you...i don't rly get the question b/c idk how the diagram looks like.....i wish we could make a diagrams on computers

First should know that if

I used 80 because that is the degree measure of arc ABC, and if the radius is 12cm, then the circumference is (diameter times pi) 75.36.

Then you can cross multiply to get 80(75.36)=360x. 6028.8=360x.

x (or the length of the arc) = 16.75 cm. Am I correct?

I used 80 because that is the degree measure of arc ABC, and if the radius is 12cm, then the circumference is (diameter times pi) 75.36.

Then you can cross multiply to get 80(75.36)=360x. 6028.8=360x.

x (or the length of the arc) = 16.75 cm. Am I correct?

message 1:by Priya (new)