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/sci/ - Science & Math

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File: 3 KB, 113x290, Triangle1.gif [View same] [iqdb] [saucenao] [google]
1088429 No.1088429 [Reply] [Original]

I've got a puzzle for you, /sci/ find the value of x, using only elementary geometry. No cheating by looking it up, and if you already know, don't give the answer away right away.

It took me many, many hours and pieces of paper to work out how to do it. Enjoy being frustrated.

>> No.1088454

faggot

>> No.1088479

Fuck. Started out easy... now I'm stuck. Hint?

>> No.1088498

>>1088479

Don't be afraid to draw extra lines.

>> No.1088563
File: 9 KB, 224x577, adfsdf.png [View same] [iqdb] [saucenao] [google]
1088563

x = 10

>> No.1088596

>>1088563
lol at 200 degrees triangle

>> No.1088609

>>1088563

Lol, not quite.

>> No.1088619

>>1088596
lol at can't count

>> No.1088649

>>1088596
>>1088609
>>1088619
lol at lol

>> No.1088650

aw man i miss 8th grade =[

>> No.1088673

>>1088650

Actually try it. I'm in university studying Mathematics, and I had difficulty doing it. Don't just dismiss it because it's geometry.

>> No.1088675

> using only elementary geometry
trig faggots do u no it

>> No.1088684

>>1088675

That isn't the puzzle, though.

>> No.1088702

>>1088673

I don't have time to do it right now, but it just looks as something that takes a lot of time due to having lots of factors that need to be calculated.

It doesn't look like a "hard" problem.

>> No.1088768

I solved it! Wow I'm prooud if myself :)

>> No.1088792
File: 18 KB, 113x290, skitched-20100602-155602.jpg [View same] [iqdb] [saucenao] [google]
1088792

I got here... and then i figured I could set up an equation seeing as the last angle missing is of course related to x and so I got

20+150+x+(180-x-50) = 180

but this just simplified down to cancel out the x's of course.
im stuck. and im also in 11th grade. so, someone want to improve on this?

>> No.1088797

I got it to 30. If thats false there are several solutions.

>> No.1088808

>>1088619
because 130+50+20 is not 200 ?? since when has this happened to math

>> No.1088838

>>1088792
CDB is 140 and CEA is 150, not the one by it.

>> No.1088848

>>1088797

I got 20. Post your method.

>> No.1088850

>>1088838

shit you're right

>> No.1088855

10

>> No.1088897

bumping because I'm stuck and demand answers

>> No.1088906

i did it! though i got stuck at the end and had to just guess/check :|

>> No.1088912

>>1088848
i also got 20.
guess/check method

>> No.1088966

>>1088897

OP here. I just found a flaw in my previous proof, so I have to start again.

I don't think guess/check counts...

>> No.1089007

>>1088429

Using simultaneous equations I get multiple answers?!?!?!?!

>> No.1089028
File: 118 KB, 571x1465, triangle.jpg [View same] [iqdb] [saucenao] [google]
1089028

30

>> No.1089029

>>1089007
there is a range of answers to the question

>> No.1089067

>>1089028

thoughts?

>> No.1089073
File: 30 KB, 365x357, Shirtrollin.jpg [View same] [iqdb] [saucenao] [google]
1089073

ohlookitsthisthreadagain.jpg

>> No.1089099

I've seen this before, It can only be done by drawing new lines and extending the current ones out side of the figure.

>> No.1089107

>>1089028

>>1089099 here, so I'm wrong? Is 30 incorrect? Looks good to me.

>> No.1089115

>>1089099
u dont have to draw a fucking thing

>> No.1089112
File: 84 KB, 571x1465, 1275510271554.jpg [View same] [iqdb] [saucenao] [google]
1089112

>>1089067

>> No.1089122

>>1089107
Try setting it to 40 and resolving all the angles, does it still work?

>> No.1089147

>>1089112
What he said

>> No.1089152

>>1089112
You're just a dumbass. Maybe you should review the properties of parallel lines that you should have learned in middle school.

>> No.1089155

>>1089028

How did you get CDE and EDB?

>> No.1089163

FFFFFFFFFFUUUUUUU 10 and 20 both work by guesscheck, so there is no definitive answer, not enough info in question.

fail.

>> No.1089172

If this really interested me, I would try.

>> No.1089190

>>1089152

I remember the properties of parallel lines. None of them can give you any of the circled numbers. Troll harder.

>> No.1089196

you guys are my convex love

>> No.1089191
File: 20 KB, 295x506, hardcirclefinal.png [View same] [iqdb] [saucenao] [google]
1089191

x = 20 niggers

>> No.1089205
File: 7 KB, 336x664, 1275506184426.gif [View same] [iqdb] [saucenao] [google]
1089205

x+y=130
but it seems there is an infinite number of solutions.

>> No.1089199

wait...was this a troll? there is no answer to get to, so is it just like posting an unsolvable sudoku to try and piss people off? hey that might work...
lol, ill make one where its possible to get right close to the end, and then it stops working, hahahahah!

>> No.1089213

>>1089190
actually from the properties you can get the: 80's, 70's, 100's, 60's and 110's
Just not the 40's and the 30

>> No.1089220

>>1089191
here
>>1089099
that was me too

>> No.1089241

yeh but that picture doesnt help, still an infinite set of answers, drawing the extra circle and triangle is pointless.

>> No.1089245

>>1089191

I'm not sure if you can use a circle... I dunno.

And yes, it is solvable. It was featured in some newspaper. I believe there are a number of methods.

>> No.1089255

>>1089213

It was never indicated that those lines were parallel to the base, much less each other, but I can see what you mean.

>> No.1089259

well how is it solvable if 10 works, and 20 works? if there was only 1 answer, they couldnt both work.

QED, bitches.

>> No.1089320

Does anyone have evidence that there are not an infinte number of answers to this?

>> No.1089344

>>1089320
If you look at a to scale version, there is no way to construct multiple versions of the figure. There is enough information that you will create the same one every time.

>> No.1089357

>>1089320

http://thinkzone.wlonk.com/MathFun/Triangle.htm

That was where I got it from, and he makes out like there is only one solution. Doesn't actually post it, however.

>> No.1089372

>>1089320
The only reason people think there are an infinite number of solutions is because they are trying to brute force the question using only the angle measures. The problem with this method is that those angle measures aren't sufficient to give the shape in the diagram, they are only necessary conditions. So when you go through the calculation, you are getting angle measures that satisfy equations, but those equations are not sufficient to generate the diagram in the picture.

>> No.1089447

>>1089372
so

>only elementary geometry
>trigonometry

Not contradictory at all :/

>> No.1089480

>>1089447
You do realize that angle measures are not trig. You can prove using elementary geometry that the sum of the angles in a triangle is 180. Nothing in what I said uses any information outside of elementary euclidean geometry.

>> No.1089487

>>1089372
So what is sufficient to produce the image then? I've drawn it out to scale now and it does look like there must be only one answer, but I have no idea what to do to obtain it. There must be some neat little trick that will produce the answer.

>> No.1089529

>>1089028
This is right. The entire thing is equilateral, so you can draw a parallel line through it, making a similar triangle of 20-80-80. From there it's child play.

>> No.1089535

>>1089487
There's no neat trick. You actually need to go through and construct some triangles in the diagram and use triangle congruences to get the answer, which is x=20 by the way.

>> No.1089553
File: 17 KB, 359x668, 20.png [View same] [iqdb] [saucenao] [google]
1089553

It's 20. I used trig to solve it, so it's not "elementary geometry" but there is only one answer.

To scale pic related.

>> No.1089572

>>1089553

How did you "use trig to solve it" without a single length given?

I think you mean you "used google to solve it"

>> No.1089589

>>1089572
I made the base of the triangle 1 and just went from there. I didn't fill any of that in since it would just be a mess of decimals.

>> No.1089587

>>1089535
Well it seems the trick would be to construct lines parallel to the bottom of the largest triangle.

>> No.1089595

>>1089572
It's an isosceles triangle.

>> No.1089611

>>1089587
I'm pretty sure the person who employed that method had to make an assumption somewhere to finish. Because you need more info than just making parallel lines to finish it.

>> No.1089613

>>1089589

thanks I'll try that

>> No.1089638

>>1089613

Not really a solution to the problem, though.

>> No.1089660

>>1088429

Just got here. Construct parallels to AB at E and D, and just fill in angles by the ass-load using similar triangles and supplements/complements.

>> No.1089790
File: 7 KB, 336x664, 1275506184426.gif [View same] [iqdb] [saucenao] [google]
1089790

with x+y=70
and then ?

>> No.1089804
File: 49 KB, 1025x769, blah.jpg [View same] [iqdb] [saucenao] [google]
1089804

20.

>> No.1089826

>>1089790

Yeah, it doesn't work.

>> No.1089860

This triangle problem has been postet so often, here's the solution:
http://blogs.sun.com/simford/entry/solved_the_world_s_hardest

>> No.1089993
File: 214 KB, 1280x1678, trianglezz.jpg [View same] [iqdb] [saucenao] [google]
1089993

I used trig to solve it. I have no fucking idea how to solve it using geometry. Here is my proof. 20 degrees is the correct answer

>> No.1090009

>>1089993

>using only elementary geometry

fail

>> No.1090033

>>1089993

i dont get it

>> No.1090056

its 10* degrees

>> No.1090101

>>1089028

No. Replace 30 with 20 and adjust effected angles and it still works. answer is 20

>> No.1090165

i got a 4 way simultaneous equation.

lawl.
tiem to solve that shit.

>> No.1090438

>>1089790
That was the same problem I ran into using that method.

>> No.1091152

sigh