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We start with the triangle PQR.
The median of a triangle
is a line segment
linking the midpoint of a side to the opposite
vertex.
There are therefore three possible medians, and this shows one of them. The other two can be drawn in a similar fashion.
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| In the first four steps we create the
perpendicular bisector of PQ.
See Constructing a perpendicular bisector of a line segment.
This establishes the midpoint of a side. |
| 1. With the compass point on any vertex, set the compass width to about two thirds the length of
either triangle side from that point. In this example, we pick point P and the side PQ. |
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| 2. Draw an arc above and below the selected side. |
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| 3. Without changing the compass width, place the compass point on the other end of the selected side,
and make two more arcs so they intersect with the first two. |
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| 4. Draw a line between the points where the arcs cross. This will bisect the triangle side, dividing it into two equal parts.
Label this point S. |
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| We then simply draw a line from the midpoint to the opposite vertex. |
| 5. Draw a line between S and the vertex opposite - in this case the point R. |
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6. Done. The blue line SR is one of the three possible medians of the triangle PQR.
The other two can be constructed in a similar way |
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