Geometry Brainteaser

[ShooterMcGavin]

Solve this problem using elementary geometry rules only, no trig(law of sines/cosines etc).

Solve for the angle a.

[rickgiblin]

80 degreese... i think

[rickgiblin]

yea, am i rite?

[ShooterMcGavin]

^^^not even close...

[DJ XtRaK©]

30?

EDIT: I DID ALL OF THE WORK AND LAWS ON IT! SO THE "?" IS ASKING TO SEE IF IT IS RIGHT!

[Doppelgänger]

30*

If its 30.. i get it right because i didnt have a "?" next to my answer :D

[uproot]

20, 25?

[DJ XtRaK©]

30*

If its 30.. i get it right because i didnt have a "?" next to my answer :D

refer to my post....!

[Hulud]

i answered the wrong angle lol

[ironchef]

Hes right the answer is 30.

[ATK_Designs]

Could be any number. :o

[Cato ED-6]

I'm guessing 40. but I'm still thinking.

Edit: is the awnser really 30?

[Doppelgänger]

oh yeah... BLAM... heres how i got it!!!

http://i99.photobucket.com/albums/l281/teamFBG/triangleproblem-2.jpg

[Doppelgänger]

refer to my post....!


I had my reply to that before you edited it :D :D :D :D

[ShooterMcGavin]

ANSWER IS NOT 30, are any of you actually working this out?

[ShooterMcGavin]

oh yeah... BLAM... heres how i got it!!!

http://i99.photobucket.com/albums/l281/teamFBG/triangleproblem.jpg

and HOW did you get that?

[DJ XtRaK©]

guess what....i got it right first bro! DONT MESS WITH A MATH MAJOR DUDE!

[Doppelgänger]

i fixed the angle that was missing..

[ironchef]

and HOW did you get that?Simple.

[rickgiblin]

ooo... sorry, i answered for the wrong "a"... this question was misleading, i want a nother question...lol. but i thought you ment the blue a on the outside of the triangle

[uproot]

the one outside of the triangle is "A", not "a" :D

[Doppelgänger]

okok.. i forgot another angle in my mad paint skills... but its all fixed now.

so verify that i did it right...

[Doppelgänger]

guess what....i got it right first bro! DONT MESS WITH A MATH MAJOR DUDE!yeah..well... i havent exercised what i learned in school in years... been 7 yrs since i have been in a classroom... :thinking:

[ShooterMcGavin]

this is not as simple as y'all think, i promise, i spent 30 min on it and couldn't figure out the last part (mathematically, i ended up getting it through trial and error).

[ATK_Designs]

By using simple adding and subtracting, it could be any combination of numbers (for the last part if you know what I'm talking about).

[DJ XtRaK©]

SO WHATS THE FUCKING ANSWER!?!?

[DJ XtRaK©]

yeah..well... i havent exercised what i learned in school in years... been 7 yrs since i have been in a classroom... :thinking:

you coming out tonight? if you do i going to bring my calculator and hit you with it!

[ShooterMcGavin]

answer is 20

[Cato ED-6]

answer is 20

could you explain?

[ShooterMcGavin]

well u can use basics of geometry to figure out all the angles pretty much. but i got left with angle cdb = 140 and cea = 150. from there i couldn't figure it out mathematically anymore and just used trial and error to get the correct angles that make up cdb and cea.

[Cato ED-6]

did you get this from a website or was it a problem someone just gave you?
if its a site, could you give me it, I would like to see how they did it in full.

You're pretty smart man.http://forums.importatlanta.com/images/smilies/goodjob.gif

[~The_Duke~]

well u can use basics of geometry to figure out all the angles pretty much. but i got left with angle cdb = 140 and cea = 150. from there i couldn't figure it out mathematically anymore and just used trial and error to get the correct angles that make up cdb and cea.

but with out trail and error you wouldnt have been able to figure it out...trail and error if I am not mistaken isnt a geometry tatic it is an alg one...so :tongue1:

[ShooterMcGavin]

^^^i already admitted that, thnx for pointing that out again geniOus...

[ShooterMcGavin]

did you get this from a website or was it a problem someone just gave you?
if its a site, could you give me it, I would like to see how they did it in full.

You're pretty smart man.http://forums.importatlanta.com/images/smilies/goodjob.gif

i got this from another forum i frequent, still waiting for the "official" answer. i wish i could claim i was smart but i didn't get it the way i was supposed to :no:

[~The_Duke~]

^^^i already admitted that, thnx for pointing that out again geniOus...

damn...leave me alone I cant pass precal to save my life...

[ShooterMcGavin]

^^^rofl, just stick to ur nightshifts dammit :D

[Ran]

Math f*cking sucks. Primarily because I'm horrible at it and because 85% of it is worthless sh*t I'll never get to use.

[~The_Duke~]

One answer that works is 50 :goodjob:

I am going to list out all the angles...

oh I called the intersection point of lines DB & EA point F...

[~The_Duke~]

Angle CAB = 80
Angle CBA = 80
Angle ACB = 20
Angle AEC = 10
Angle EAB = 70
Angle DBA = 60
Angle AFB = 50
Angle DFE = 50
Angle DFA = 130
Angle EFB = 130
Angle ADB = 40
Angle CDE = 60
Angle AEB = 30
Angle DEC = 100
Angle BDE = 80

Which in turn makes Angel a = 50

If you add the values of AEB (30) + DEC (100) = 130 + 50 = 180

[ShooterMcGavin]

Math f*cking sucks. Primarily because I'm horrible at it and because 85% of it is worthless sh*t I'll never get to use.
an azn bad at math? wtf is wrong w/u? :thinking: :lmao:

[~The_Duke~]

an azn bad at math? wtf is wrong w/u? :thinking: :lmao:

There is a line in a steven lynch song that prolly happened to him when he was small...

"momma dropped him on his head, now he thinks he is a peice of bread"

either that or his math teachers have always worn lots of perfume and he just pasted out when they walked into the room...

VVVVV pic of my answer

[ATK_Designs]

Let's look at it this way:

At point E, we have 3 angles, E1 = unknown, E2 = a(which we want to know) and E3 = 30. Same goes for D's angles, D1 = unknown, D2 = Unknow, D3 = 40 (calculated).

From Calculations by using simple means of adding and subtracting, we results in E1+E2(a) = 150 and D1+D2 = 140

Therefore, if you give any number to E2(a), the rest will work out mathematically because they'll fit right in.

For example:

If E2(a) = 10, therefore E1 = 150-10 = 140. Then D1 = 180 - (140+20) = 20.

Then D2 = 140-20 = 120.

So for the top triangle, we have 20, 140, 20, and for the middle angle (aka a's triangle), we'll have 120, 10, 50, which mathematically, all added correctly.

Try using any combinations, and they'll come out to match up perfectly.


So the "truest" way to contruct the triangles using the correct measurements and measure the correct angle would be using a ruler and measure it. By using simple addition, subtraction, and subtitution, you can't truly find out the right angle because of the reason explained above.

[~The_Duke~]

Let's look at it this way:

At point E, we have 3 angles, E1 = unknown, E2 = a(which we want to know) and E3 = 30. Same goes for D's angles, D1 = unknown, D2 = Unknow, D3 = 40 (calculated).

From Calculations by using simple means of adding and subtracting, we results in E1+E2(a) = 150 and D1+D2 = 140

Therefore, if you give any number to E2(a), the rest will work out mathematically because they'll fit right in.

For example:

If E2(a) = 10, therefore E1 = 150-10 = 140. Then D1 = 180 - (140+20) = 20.

Then D2 = 140-20 = 120.

So for the top triangle, we have 20, 140, 20, and for the middle angle (aka a's triangle), we'll have 120, 10, 50, which mathematically, all added correctly.

Try using any combinations, and they'll come out to match up perfectly.


So the "truest" way to contruct the triangles using the correct measurements and measure the correct angle would be using a ruler and measure it. By using simple addition, subtraction, and subtitution, you can't truly find out the right angle because of the reason explained above.

I didnt catch that draw a pic of what you mean...

[ATK_Designs]

Here, please allow me to use your pic (Duke)

[~The_Duke~]

So in other words what you are saying is also long as you adjust the unknown values correctly a could be just about anything (with in reason according to the known values)?

[ATK_Designs]

So in other words what you are saying is also long as you adjust the unknown values correctly a could be just about anything (with in reason according to the known values)?

yes, mathematically, E2 (aka "a") could be anything from 1 to 149 degrees and it'd still be within the calculations. :yes:

[~The_Duke~]

yes, mathematically, E2 (aka "a") could be anything from 1 to 149 degrees and it'd still be within the calculations. :yes:

That is what I thought, but i didnt want to spend that much time sitting there and proving that theory, instead I just found one that worked and wrote it down lol

I bet I could write a C++ to prove it for me lol

[krindus]

i don't necissarily agree with that, i believe 20 degrees is closer to the right answer. after trying the math and not being able to get a conclusive answer, due to multiple unknowns in the equations, i turned to cad, drew the triangle, and it measured out to 20 degrees. realistically, the only true way to find this answer is to set a lenght of at least one side, and use trig. otherwise it's a pointless question, it has a deffinant answer but is impossible to find with the given standards

[ATK_Designs]

i don't necissarily agree with that, ....realistically, the only true way to find this answer is to set a lenght of at least one side, and use trig. otherwise it's a pointless question, it has a deffinant answer but is impossible to find with the given standards

Isn't that what I said above?

[~The_Duke~]

There is no one answer to this problem...the answer is a range of values cas as long as it doesnt equal 0 or less than zero and doesnt equal 150 or greater it will work...

[ShooterMcGavin]

^^^i for one don't believe that's true, i'll post up the right answer once i find it...

[~The_Duke~]

^^^i for one don't believe that's true, i'll post up the right answer once i find it...

If you read the theroy that interlude had it makes perfect sense...I mean just pick random numbers and see if it works...