7.+Basic+Constructions

=Basic Constructions= Objective: To use a compass and a straightedge to construct congruent segments and angles and bisect segments and angles.

Standards
Visit Standards page to identify numbers. NCTM Standards: 3, 4 CT Mathematics Standards: 1.3(a), 2.1, 2.1, 3.1, 3.2a(1)

In a //construction// you use a //straightedge// and a //compass// to draw a geometric figure. Let's learn how to copy and bisect both a segment and an angle. For this activity, you will need your own straightedge and compass and some paper.

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The segment that you drew that bisected the first segment is called a //perpendicular line//. These two lines form a right angle. Because our line bisected the segment at the midpoint, it is a //perpendicular bisector.// A bisector will cut a segment into two congruent segments.

Try this online activity where you act as an urban planner using segment bisectors to determine where to place a hospital: []

An //angle bisector// is a ray that divides an angle into two congruent coplanar angles. Its endpoint is at the angle vertex.

Try something different - construct bisectors without a compass and straightedge: []

A reading assignment - The History of Geometric Constructions at []. Try doing three of the constructions, and then elaborate on your experiences in the discussion tab.