1. Copy a segment Copy an angle
Basic Constructions
Copy a segment
Copy an angle

2. What is a Construction? Uses TWO instruments only
Compass
Straightedge
Since a compass measures the radius of a circle, and radii of a circle are congruent, then we can use it to construct congruent segments.
A straightedge is used to connect two points. A ruler may not be used to measure distances in constructions.

3. What is a Construction? Definition: An arc is any part of a circle.
When we draw using a compass we will be drawing arcs. We rarely need to complete the entire circle. The radii will still be congruent even if a complete circle is not present.

4. Construction #1: Copy a Segment
Given , construct a segment congruent to on line l.
Step 1: Use the straightedge to draw a line and label it l A B
Put compass point here
Step 2: Choose any point on l and label it C.
Step 3: Set the compass at A and make an arc at B.
Step 4: Using the same opening, set your compass at C and make an identical arc so that it intersects line l. Label this point D. l C D
Put compass point here

5. Construction #2: Copy an Angle
Step 1: You need to start with a line l and a point F which corresponds to C. C E
Step 2: Opening your compass to any comfortable distance, set the compass at C and make an arc that intersects both sides of the angle. Label these points E and D.
Put compass point here D
Put compass point here
Step 3: Using the same opening, set the compass at F and make an identical arc which intersects the line l. Label this point G.
Put compass point here
Step 4: On the original angle, set the compass at D and make an arc that intersects the other side of the angle at E. F l G

6. Construction #2: Copy an AngleD E
Step 5: Using the same opening, set your compass at G and make an identical arc so that it intersects the arc from step 3. Label this point H.
Step 6: Draw H F G
Put compass point here