1. Warm-up 3.1 Constructions and 4.1 Triangle Sum Theorem
1) Name the corresponding angle(s) to . 2) Name two pairs of alternate exterior angles. 3) Name all angles congruent to LMD. 4) What is the relationship between ?

2. Student of the day! Block 4

3. Student of the day! Block 5

4. Student of the day! Block 6

5. Start of Constructions
Constructions involve using a compass and straightedge.
No measuring with rulers or protractor.
Copying a segment.
1) Put one end of the compass one end of the segment .
2) Stretch the compass to the other end and draw an arc.
3) With a straightedge draw a long straight line.
4) Using the same compass setting from 2) draw the arc with
the compass end on the end of the line you just drew.
When copying segments and angles always start with a ray.

6. Copying an angle
1) Draw an arc through the original angle. 2) Use your straightedge to draw a line. 3) Using the same compass setting from 1) draw an arc through the line in 2) 4) Use the arc drawn across the original angle from 1) to measure across the angle using the compass. (Draw a small arc to mark the intersection at the top. Keep that compass setting. 5) On the line with arc drawn for 3) use the intersection at the bottom to draw the intersection above with the compass. 6) Connect the end of the line segment with the intersection from 5).

7. Copying an obtuse angle using linear pairs

8. Prove: Triangle Sum Conjecture
4.1 Triangle Sum Theorem
 Prove: Triangle Sum Conjecture
  Given: Line EB
is parallel to
Segment AC
Two Column Proof:

9. 4.1 Continued…
C-17 Triangle Sum Conjecture
The sum of measures of the angles in every triangle is ______.

10. H.W. Assignment
3.1 pg 147 #1-4 To get credit on the 3.1 homework, you must show compass marks. If you do not leave the arcs, you will not get credit. 4.1 pg 203 #2-9