Help me answer this problem:
The side lengths of a triangle are 5, 11, and 6.
I have to determine if the triangle is right , acute , obtuse or not a triangle.
I tried to do this:
Pythagorean theorem: a^2+b^2=c^2
5^2+11^2=6^2
25+121=36
146=36
146>36
146>c isn't it?
the answer is that its NOT a triangle.
But how the hell?
Shouldn't it be acute since c^2<a^2+b^2, c<146?
Please help me, I've spent about 5 hours trying to figure this out, I might kill myself.

Well to start off c is supposed to be the longest side of the triangle. So you should set it up as 5^2+6^2=11^2.

It is obtuse, since 61<121

No, I just finished this unit a few weeks ago. It would not be a triangle, since the first step is trying to figure out if it actually is a triangle, which it isn't, considering 6+5=11, which does not allow it to be a triangle.

>>5 greater or equal

so it is a triangle

>>5 then explain a right triangle mother fucka!

In review: It IS a triangle, but not a right triangle.
OP used Pythagorean theorem to determine if it was a triangle at all while Pythagorean theorem applies ONLY to right triangles.
OP also put the lengths out of order in his original model, because c2 is always the LONGEST of the lengths.

I assume you're attempting to apply a previous year's method to a current year's problem. Use the SSS model of Soh Cah Toa.

well since there is 3 sides given to you, use the Law of Cosines(if you dont know google it) twice to find 2 angles then subtract the sum of those two by 180 and tada! there's your answer! (sorry I know I didn't show numbers or anything but before i forget when you use the law of cosines to find the angle use algebra to find the angle side ok?)

>>7 Actually, that's incorrect. If both smaller sides add up to exactly the length of the longest side, then the shape would be a segment, not a triangle. >>5 is correct.

If you so request, this can be proven via a variety of methods that I don't feel like posting right now.

Its not hard, I just did this in class last week. this is simple algebra.
5^2+6^2=11^2.
25+36=121
61=121
61 is not equal to 121. Therefore this is not a right triangle.
It isnt a triangle at all because >>5

triangle check eqs.
Turns out I was wrong.

I remember those trick questions, but they fade out once you get into higher level math. Since the trick is knowing all the steps to a 30 minute problem, not the what if questions.

One side plus another side must equal more than the third side, or else the triangle would not be able to connect

when i read the thread my head make BOOM :D

wouldnt it have to be a triangle so that you can use pythagreon theorom on it or........would that just drive home the fact that its not a triangle?What class are you in kid?

It sounds like geometry, since trig focuses more on the functions, not what makes a triangle. Though the pythagorean theorem isn't just for triangles, for it is used in 3 dimensions for many things.

People the question has been answered multiple times. You can stop answering.

People could actually close this.