Why does obtuse traingle = a^2 b^2 + c^2 and acute triangle = a^2

Question

Why does obtuse traingle = a^2 > b^2 + c^2 and acute triangle = a^2 < b^2 +c ^2? What is a, b and c in each case? What exactly is < or > mean? Thanks! :)

isaiah.feynman · Answer

Any diagrams perhaps?

isaiah.feynman · Answer

< means "less than"
> means "greater than"

anonymous · Answer

I saw someone answer this on another openstudy question. One moment, I'm trying to find it.

campbell_st · Answer

based on angles there are 3 types of triangles

acute

right 

obtuse

so any triangle can be classified by applying pythagoras' theorem 

$$a^2  = b^2 +c^2 $$

is a right triangle... 


the looking at what you posted you have the theorem fro obtuse and acute angled triangles..

hope it helps

anonymous · Answer

I understand right angled traingles but I don't understand obtuse or acute. I couldn't find the exact question, but let's use this previous question as a base: http://openstudy.com/study#/updates/50b6beb2e4b07527f06b1479

anonymous · Answer

7, 15 and 21 lengths - what triangle does it form?

campbell_st · Answer

ok

so the longest side is the hypotenuse so 

$$21^2 = 441$$

and 

$$7^2 + 15^2 = 274$$

so 

$$21^2 > 7^2 + 15^2$$

which means the triangle is obtuse

anonymous · Answer

Thank you Campbell, I understand now! Before I close my question, may I ask what is a acute triangle and what is obtuse?

anonymous · Answer

Thanks for helping too, Isaiah.Feynman :)