Arc Arrow 1
- Ryan Hirst
The arc is oriented. It respects the equivalence of these three statements: Arc BC subtends central angle BAC, There is a one-to-one correspondence between points on arc BC and points on segment BC. The arc respects minimum rotation. We may then preserve measure: |BC| (magnitude) is the distance from B to C (direction). |∡BAC| (magnitude) is the angle from B to C (direction/sign).
NOTES: Point E is chosen for simplicity To display correctly, the direction of the arrowhead depends on the screen size of radius AB. → λ should increase as the radius decreases. But zooming (scroll wheel) will screw it up. To get consistent behavior, I use a 32 px square image in the bottom left corner to calculate the pixels per GGB unit: ppu = 32/x(crn3-Corner) Then the radius AB, in pixels, is (AB ppu) And the definition works without further ado. _______ Tool (.ggt): http://www.geogebratube.org/material/show/id/65947 ArcArrow1[A, B, C, λ] Return the (signed) angle of the same arc Construction: http://www.geogebratube.org/material/show/id/99837 Tool (.ggt): http://www.geogebratube.org/material/show/id/99838 Angle2[B,A,C]