Fri Feb 08, 2008 10:17 am   Reply with quote         

Fri Feb 08, 2008 10:17 am   Reply with quote         

But I am not that good in math, so......

Fri Feb 08, 2008 10:21 am   Reply with quote         

OK I know now what a decagon is.... judging by the image above. What was it you want to do with it now????

Fri Feb 08, 2008 10:45 am   Reply with quote         

I misunderstood the original question. I thought they wanted to know the sum of the interior angles of the original decagon. Then I saw Anna's image.

annajon wrote:

OK I know now what a decagon is.... judging by the image above. What was it you want to do with it now????

Using Anna's diagram it seems that you'd take 180 degrees (EVERY triangles interior angles = 180) times the number of triangles and that would give you the sum of all the resulting angles in the joined vertices.

_________________
Why I do believe it's pants-less o'clock! - Lar deSouza
”The mind is like a parachute, it doesn’t work if it isn’t open.” - Frank Zappa
Created using photoshop and absolutely no talent. - reyrey

Fri Feb 08, 2008 11:14 am   Reply with quote         

Doesn't the old easy multiply the final amount by 100 + % work. For the 10% percentage 22.44 x 110% = 2468. Move dec to left 2 spaces 24.68 then 24.68 x 115%= 2838. move dec over 2 spaces and $28.38 ??

Okay the last was sales tax that was added. Not second discount. I see!

Fri Feb 08, 2008 12:07 pm   Reply with quote         

Martrex wrote:

Doesn't the old easy multiply the final amount by 100 + % work. For the 10% percentage 22.44 x 110% = 2468. Move dec to left 2 spaces 24.68 then 24.68 x 115%= 2838. move dec over 2 spaces and $28.38 ??

No Martrex, first you had a discount, that made it 85%, and after that you had a 10% increase in price that made it the NEW 100% aka 22.44 USD.

That is what you need to work back to the original price.

Fri Feb 08, 2008 12:12 pm   Reply with quote         

TofuTheGreat wrote:

I misunderstood the original question. I thought they wanted to know the sum of the interior angles of the original decagon. Then I saw Anna's image.

annajon wrote:

OK I know now what a decagon is.... judging by the image above. What was it you want to do with it now????

Using Anna's diagram it seems that you'd take 180 degrees (EVERY triangles interior angles = 180) times the number of triangles and that would give you the sum of all the resulting angles in the joined vertices.

Not being American myself, and not good at math, what is meant by Vertices in my image? Are all the parts not joined already? Or are we to take the whole thing apart and stick the flat sides together to make bigger squares?

Math is no fun at all.......

Fri Feb 08, 2008 5:46 pm   Reply with quote         

TofuTheGreat wrote:

I misunderstood the original question. I thought they wanted to know the sum of the interior angles of the original decagon. Then I saw Anna's image.

annajon wrote:

OK I know now what a decagon is.... judging by the image above. What was it you want to do with it now????

Using Anna's diagram it seems that you'd take 180 degrees (EVERY triangles interior angles = 180) times the number of triangles and that would give you the sum of all the resulting angles in the joined vertices.

....but NOT if the triangles meet in the centre like that. To get the sum of the angles in a decagon, you could only get 8 triangle if you did this sort of thing..

hence 8 x 180 =1440

Fri Feb 08, 2008 5:57 pm   Reply with quote         

bigbuck wrote:

TofuTheGreat wrote:

I misunderstood the original question. I thought they wanted to know the sum of the interior angles of the original decagon. Then I saw Anna's image.

annajon wrote:

OK I know now what a decagon is.... judging by the image above. What was it you want to do with it now????

Using Anna's diagram it seems that you'd take 180 degrees (EVERY triangles interior angles = 180) times the number of triangles and that would give you the sum of all the resulting angles in the joined vertices.

....but NOT if the triangles meet in the centre like that. To get the sum of the angles in a decagon, you could only get 8 triangle if you did this sort of thing..

hence 8 x 180 =1440

Isn't that what I said?

blue_lurker wrote:

The second I don't understand hoping some one will explain it to me

2. By joining all the vertices of a decagon, how many diagonals are formed, what is the sum of all the angles of a decagon.

I suppose it depends on the meaning of the phrase "joining all the vertices of a decagon". Are we joining each vertice to the others? Like so:

If so then we're not creating triangles and the sum of the angles goes WAY up.

_________________
Why I do believe it's pants-less o'clock! - Lar deSouza
”The mind is like a parachute, it doesn’t work if it isn’t open.” - Frank Zappa
Created using photoshop and absolutely no talent. - reyrey

Fri Feb 08, 2008 6:01 pm   Reply with quote         

the sum of a decagon is 1440....each segment is 144*....x 10....you have to take the 36* congruencey from the 180* total tofu is talking about.

Fri Feb 08, 2008 6:01 pm   Reply with quote         

See, math is comfjusing ... my head is spinning.....

Fri Feb 08, 2008 6:03 pm   Reply with quote         

dewdew wrote:

the sum of a decagon is 1440....each segment is 144*....x 10....you have to take the 36* congruencey from the 180* total tofu is talking about.

At least I got the sum for the price right!!! phew!!!!!

Fri Feb 08, 2008 6:12 pm   Reply with quote         

TofuTheGreat wrote:

bigbuck wrote:

TofuTheGreat wrote:

I misunderstood the original question. I thought they wanted to know the sum of the interior angles of the original decagon. Then I saw Anna's image.

annajon wrote:

OK I know now what a decagon is.... judging by the image above. What was it you want to do with it now????

Using Anna's diagram it seems that you'd take 180 degrees (EVERY triangles interior angles = 180) times the number of triangles and that would give you the sum of all the resulting angles in the joined vertices.

....but NOT if the triangles meet in the centre like that. To get the sum of the angles in a decagon, you could only get 8 triangle if you did this sort of thing..

hence 8 x 180 =1440

Isn't that what I said?

blue_lurker wrote:

The second I don't understand hoping some one will explain it to me

2. By joining all the vertices of a decagon, how many diagonals are formed, what is the sum of all the angles of a decagon.

I suppose it depends on the meaning of the phrase "joining all the vertices of a decagon". Are we joining each vertice to the others? Like so:

If so then we're not creating triangles and the sum of the angles goes WAY up.

yeah C, I'm not really sure on the question either. I'd guess it's a two part thing where you are looking for patterns related to the number of sides of a polygon. Stock standard year 9 introductory algebra thing.

Rather than work on the decagon, trying to count/add stuff. Look for common patterns on smaller polygons and see if you can derive the rule (or formulae) which relates 'no. of sides to sum of angles' or 'no. of sides to total diagonals'.

I think the question is as much about basic algebra as it is geometry.

Fri Feb 08, 2008 9:11 pm   Reply with quote         

TofuTheGreat wrote:

that's what i understood the question to mean

Fri Feb 08, 2008 9:23 pm   Reply with quote         

dumbat wrote:

TofuTheGreat wrote:

that's what i understood the question to mean

Ah - yes that makes sense. I was picturing a 3D thing for a decagon, though....