Given:line m which contains point a
Steps
1. Place compass tip at point A. Using any compass opening less than the length of m, draw two arcs intersecting line m on both sides of A. Label this points C and D
2. Place compass tip at point C. Udjust the compass opening, so that it is greater than 1/2 CD and draw an arc above m.
3. Using the same compass opening, place compass point at point D. Draw an arc above m intersecting your first arc.
4. Label the intersection point X.
5. Ise a straightedge to draw AX. This is perpendicular to m thorough point A
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