Class Summary- Wednesday, December 8th

 

Lesson 6-5-

 
1. Definition of a Trapezoid: It's a quadrilateral with exactly one pair of parallel sides.
 
(Notes: If it has one pair of parallel side that ate also congruent, it is a parallelogram - Theorem 6-8-  and not a trapezoid)

 
2. Bases- the parallel sides (of a trapezoid)
    Legs- The other sides (which are not parallel)
 
3. In a trapezoid, consecutive angles, one from each base, are congruent

4. Two kinds of Trapezoids:
 
Right Trapezoid- has one right angle.

                             - The consecutive angle on the same leg is also right because of Theorem 3-4 (if: the transversal of perpendicular lines is perpendicular to one parallel line, then: it is also perpendicular to the other parallel line.)

Iscosceles Trapezoid- has congruent legs.

5. Median of a Trapezoid: a segment whos endpoints are the midpoints of the legs.

6. Theorems:

T 6-14- if: it is an isosceles trapezoid,

               then: both pairs of base angles are congruent.

T 6-15- if: it is an isosceles trapezoid,

               then: the diagonals are congruent.  (Notes: that doesn't mean they bisect each other.) 

T 6-16- (if) the median of a trapezoid is:

               (then) parallel to the bases,

               AND

               (then) its measure is one-half the sum of the measures of the bases.

The Homework for tomorrow is: Page 325# 16-37 all. 

Also, you have to post your opinion about the presentation to the 1st graders (a paragraph).