Question

HELP!



If EF=12, IJ=3x-4, and HG=x, find lengths IJ and HG. (diagram in comments.)

Answer 1

Looks like the median of a trapezoid, which is equal to the average of the lengths of the bases.

Answer 2

okay...what does that mean?

Answer 3

The median, IJ, or rather the length of the median is the average of the lengths of EF and HG.

Answer 4

Do you know how to compute the average of two numbers?

Answer 5

http://en.wikipedia.org/wiki/Trapezoid (necessary formulas are there)

Answer 6

Yes, this relies on knowing this particular theorem about trapezoids. Finding the median of the trapezoid is the first step to determine its area.

Answer 7

Okay. Why doesn't my textbook cover this?

Answer 8

They expect you to go look it up?

Answer 9

I'm sure it is covered. The point of this question is to see what you remember about the theorems of trapezoids (assuming you've already studied the geometry of quadrilaterals), and to give you a little basic algebra practice to see if you remember how to solve single-variable equations (assuming you studied basic algebra before taking geometry).

Answer 10

Not necessarily, I wouldn't think trapezoids rate highly as critical learning...:-)

Answer 11

I can assure you my textbook does not cover this. At all.

Answer 12

There is definitely a tendancy to encourage students to research things for themselves, the way university students are already expected to do (in some degree)

Answer 13

It doesn't help when I suck at geometry though lol

Answer 14

Is your textbook a geometry textbook?
If so, when was it printed?
Geometry textbooks have included theorems about trapezoids for over two-thousand years, so if yours doesn't cover this, then it must be some strange recent change that has happened.
I have heard that the geometry textbooks students are using these days are very different.

But, anyway, I explained how to solve it. Do you know how to set up the equation now?

Answer 15

My book was published last year and it is a geometry textbook. Even my dad has looked it over and said it was super confusing.

Thanks for the help though. I got it from here

Answer 16

You should be thankful they are teaching you any geometry at all, these days......:-)

Answer 17

Yeah, I am to an extent. It's just that I'm home schooled and I get all of my courses sent to me. I don't have any teachers to turn to and all of my friends are too busy to tutor me. So I have to figure it out for myself which is hard because most of the time I don't understand

Answer 18

Yeah, that's a whole different ball game, needs a lot of self-discipline.
Go rooting around on the internet, there are some great geometry sites out there (even if the powers that be are cutting back on it in the curriculum.

Answer 19

I will. Thanks!

Answer 20

@estudier "You should be thankful they are teaching you any geometry at all, these days...."

Indeed. If you ever get a chance, check out the book, 'The Teaching of Geometry' by David Eugene Smith. The copyright date is 1911, so it is free to download from Project Gutenberg.
Seems they had the same issues then as now with people trying to eviscerate the geometry curriculum.

@cerabear - I highly recommend TheMathPage.com for the old-school way of learning geometry. Even better, if you can actually get a copy of Euclid's 'Elements' - I don't think you'll find a better geometry textbook. It's been the standard for thousands of years.

Answer 21

I'll take a look at the site and see if my library has 'Elements' :)

Answer 22

Euclid online ( http://aleph0.clarku.edu/~djoyce/java/elements/elements.html)

Answer 23

@estudier yes, I've used that site before, and it's pretty good. The link doesn't work because it is including the ) at the end, so to anyone trying to follow it, try copying it without the ) and then pasting it to your browser.

Answer 24

Ooops! http://aleph0.clarku.edu/~djoyce/java/elements/elements.html