View Full Version : Trisect an angle
spacefire5458
Aug 23, 2007, 12:29 PM
How do I trisect an angle using only a straightedge and a compass?
Thanks:confused:
retsoksirhc
Aug 23, 2007, 12:38 PM
Okay, lets say you've got angle abc.
I *think* that if you put the point of the compass on the vertex (b)and draw with it from one point (a) to the other(c), then put the point on (a) and the pencil on the vertex (b) and draw out toward the circle you made before, and then the point on (c) and the pencil on the vertex (b) and draw out toward the circle again, the places where the circle meets *should* be where the line go that trisect the angle.
This could very well be wrong, though. I don't remember too much from my days of geometry... that was about 7 years ago.
spacefire5458
Aug 23, 2007, 12:41 PM
That's how you bisect an angle not trisect it.
Capuchin
Aug 23, 2007, 12:53 PM
You can't trisect an arbitrary angle using just an unmarked straightedge and compasses. It's a famous result and has been proved to be impossible.
retsoksirhc
Aug 23, 2007, 01:03 PM
Dang. Well, I remembered doing Something like that to an angle with finding where circles intersected.