Hello,

I've come across a problem which asks me to prove that i can make 2009 obtuse triangles and only ONE acute triangle within a pentagon. I was thinking that there was a theory which could prove that an infinite amount of obtuse triangles can be made within a certain shape.

I have'nt got any other ideas besides that, so could anyone tell me if im on the right track or totally lost ?

Also I'd appreciate it if anyone could give me an idea to how to prove this?

Thanks in advance