Circles
Central Angles, Arcs, and Chords
Step 1
Use the LINE tool
to construct a line through Center A and Point B.
![Toolbar Image](/images/ggb/toolbar/mode_join.png)
Step 2
Construct a Point C on the circle using the POINT tool
.
![Toolbar Image](/images/ggb/toolbar/mode_point.png)
Step 3
Use the LINE
tool to construct a line through Center A and Point C.
![Toolbar Image](/images/ggb/toolbar/mode_join.png)
Step 4
Click the Point tool in the toolbar.
Then use the INTERSECTION
tool to construct Point D and Point E.
(Point D should intersect line AB and the circle. Point E should intersect line AC and the circle.)
![Toolbar Image](/images/ggb/toolbar/mode_intersect.png)
Step 5
Use the ANGLE MEASURE
tool to create and measure angle BAC and angle DAE.
*First select the point B, then center A, then select point C counterclockwise!*
*First select the point D, then center A, then select point E counterclockwise!*
![Toolbar Image](/images/ggb/toolbar/mode_angle.png)
Step 6
Use the CIRCULAR ARC
tool to create and measure Arc BC and Arc DE.
*First select the center A, then select Points B and C counterclockwise!*
*First select the center A, then select Points D and E counterclockwise!*
![Toolbar Image](/images/ggb/toolbar/mode_circlearc3.png)
Step 7
Use the Algebra window to see the measures of Arc BC (labeled "d") and Arc DE (labeled "e").
Step 8
Use the SEGMENT
tool to construct Chord "h" with endpoints B and C.
Use the SEGMENT
tool to construct Chord "i" with endpoints D and E.
![Toolbar Image](/images/ggb/toolbar/mode_segment.png)
![Toolbar Image](/images/ggb/toolbar/mode_segment.png)
Step 9
Use the Algebra Window to see the measures of Chord h and Chord i.