## babykissesconfused Group Title why must the compass opening be greater than 1/2 the length of the segment? 2 years ago 2 years ago

1. luffingsails

What is the task? If you are attempting to find the perpendicular bisector, you would need to use the two end points and find where two arc intersect above the segment. The only way this will happen is if the compass opening is greater than 1/2 the segment length. But do you have more to go on?

2. babykissesconfused

When constructing a perpendicular bisector, why must the compass opening be greater than the length of the segment?

3. luffingsails

I think I answer exactly that. When constructing a perpendicular bisector, the compass is used by creating an arc from each end point. These two arcs meet at a point which is perpendicular to and bisects the original segment. However, for these two arcs to actually intersect, the compass opening must be greater than 1/2 of the segment.

4. luffingsails

|dw:1317150552706:dw| for the two arcs to intersect, the radius must be greater than 1/2 of the original segment. Make sense?

5. amistre64

it doesnt have to be greater than half

6. amistre64

it has to be at least half :)

7. luffingsails

If it is equal to 1/2 of the segment, the point is on the segment. That only provides me with the point that splits the length in two, it does not provide me with the ability to create a line perpendicular to the segment. <wry chuckle>

8. luffingsails

Although, I could do multiple iteration of the technique using a compass opening less than 1/2 of the segment.

9. babykissesconfused

When constructing an angle bisector, why must the arcs intersect?

10. amistre64

so true, so true