Angle between two line segments

[cliverlong]

Hello

Can someone please clarify the expected behaviour?

As an introduction to radian measure, I am working up a simple .agg file to show how as the angle in a circle increases the sector's arc length increases and this can be used as an alternate way of measuring the size of the angle.

I have defined my circle parametrically. Then I drop two points on the circumference of the circle, one on the x-axis. Then I insert line segments from the centre to the two points on the circumference (radii).

Next select the two line segments (radii) and create angle between them.

Now whether or not I have "Allow reflex angle" selected or de-selected in the "Edit angle measure" dialog, the application seems to display only acute angles, either between the radii or the extended line segments. Is there any way I can define the angle so it progresses : Zero > acute > obtuse > reflex > zero (?)


Thanks

Clive

<< added >>

  agg angle between line segments.doc (Size: 31.5 KB / Downloads: 4)

[Support]

Hi Clive,

There are two ways to create an angle in Autograph:

1. Select two line segments, right-click > Angle.
2. Select three points, right-click > Angle.

You want the second method as there is then no ambiguity about which angle you want to plot. It is important to select the three points in the right order. The second point is the centre, and the anti-clockwise angle is plotted from the line created with the first point, to the line created with the third point. (It will be obvious when you create a few.)

Make sure you select "Allow Reflex Angle".

Best regards,

Simon

[cliverlong]

The "three points" method with reflex set is spot on.

Thanks,

Clive