Geometry · Congruence

Construct perpendicular bisectors

Construct perpendicular bisectors.

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What you’ll learn

Construct perpendicular bisectors.

Key idea

The opening must allow two crossings on opposite sides; equal radii give equal endpoint distances.

Two crossings from identical endpoint openings locate the bisector; a line through unequal-radius crossings need not bisect.

Worked example

Enter the exact value or ordered values in the format requested below.

Segment A=(-2, 1), B=(8, 1), length AB=10; call equal-opening arc crossings P,Q. Construct its perpendicular bisector using radius AB. Enter centers=...; arcs=...; radius=...; line=... .

  1. Using radius AB=10, both circles cross twice; midpoint horizontal coordinate 3, vertical offset squared 75.
  2. Both crossings have equal distances to A/B; line PQ is perpendicular to AB and passes its midpoint.

Answer: centers=A,B; arcs=both_sides; radius=AB; line=PQ

Quick Check

Choose which candidate representation satisfies the requirements of 'Construct perpendicular bisectors' and justify the choice.

Segment A=(0, -2), B=(4, -2), length AB=4; call equal-opening arc crossings P,Q. Candidate 1: same opening AB at A/B, arcs both sides, join P/Q. Candidate 2: arc from A only, draw AP. Candidate 3: unequal openings at A/B, join two crossings. Select with equidistance evidence.

Choose one answer

Show a hint

Use one unchanged compass opening at both endpoints.