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Copying an Angle
Instructions Click on 'Next' to go through the construction one step at a time, or click on 'Run' to let it run without stopping.
(If there is no image below, see support page.)
Note that the straightedge can be a ruler, but it is not used to actually measure anything, just to draw straight lines. Ignore the markings on it.
Step-by-step Instructions
| Step 1 |
Using the straightedge, draw a reference line and place a point P near the left end. |
| Step 2 |
Set the compass width to the distance AC, and without adjusting the compass,
place it on P and mark an arc across the line. This establishes the point Q |
| Step 3 |
With the compass on point A set its width to the the point B. |
| Step 4 |
Without changing the compass width, place the compass point on the the point P
and draw an arc above the line. |
| Step 5 |
Place the compass point on C and set its width to the point B. |
| Step 6 |
Without changing the compass width, place the compass point on the the point Q
and draw an arc across the previously drawn arc. The intersection of these two arcs becomes point R. |
| Step 7 |
Using the straightedge, draw a line from point P to R where the arcs intersect. |
| Step 8 |
Done. The angle ∠QPR is
congruent (equal in measure)
to angle ∠CAB. |
Try it yourself
Click here for a printable worksheet containing twoangle copying problems.
When you get to the page, use the browser print command to print as many as you wish. The printed output is not copyright.
Other constructions
Lines
Angles
Triangles
Triangle Centers
Circles, Arcs and Ellipses
Non-Euclidean constructions
(C) 2007 Copyright John Page
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