Bisecting a line

Bisecting a line is cutting a line exactly in half. It may also be referred to as constructing a perpendicular bisector as the line you are drawing will be at a right angle to the original line.

You will need a compass, pencil and ruler. Do not rub out any of the construction lines, these will show that you used a compass and didn't measure where the line should be.

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Bisecting a line
To bisect this line, set your compass to just over half the length of the line. Keep your compass this size for the rest of the question.
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Bisecting a line
Place your compass on one end of the line (here point B) and draw an arc that crosses the line. Do not adjust the compass.
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Bisecting a line
Place your compass on the other end of the line (point A) and draw an arc. It must cross the other arc above and below the line.
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Bisecting a line
Draw a straight line through where the two arcs intersect above and below the line. You can measure both sides of the line to check they are of equal length.
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Bisecting a line
The line drawn indicates all the points that are equidistant from point A and point B, all points to the left of this line (the area shaded blue) are said to be ‘closer to the point A than point B’ and all the points to the right of the line (shaded pink) are ‘closer to point B than point A’.

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Loci and constructions - WJECBisecting a line

Bisecting a line

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