| Start with a ray with endpoint C. The right angle will have C as its vertex. |
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| 1. Mark a point, not on the given line, about 6 cm in from C.
Its exact location is not important. Label it D. |
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| 2. Set the compasses on point D and set their width to the endpoint C . |
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| 3. Draw an arc that crosses the given line and extends over and above the endpoint C.
(If you prefer, draw a complete circle.) |
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| 4. Draw a diameter through D from the point where the arc crosses the given line,
creating points B and A. |
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| 5. Draw a line from C to the endpoint A of the diameter line |
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| 6. Done. The angle ACB is a right angle (90 deg). |
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