1. 6.5 Trapezoids A D B C A Trapezoid - a quadrilateral with:
*one pair of parallel sides (called bases)
*two pairs of base angles
*one pair of nonparallel sides (called legs)
If legs are congruent – isosceles trapezoid A D B C

2. Ex 1: Given Trapezoid ABCD with , identify the segments or angles as bases, consecutive sides, legs, diagonals, base angles, or opposite angles. A D B C c)
consecutive sides d)
diagonals
opposite angles a)
bases e) b)
legs f)
base angles

3. Thm 6.14 – If a trapezoid is isosceles, then each pair of base angles is congruent.
Thm 6.15 – If a trapezoid has a pair of congruent base angles, then it is isosceles. B C A D

4. Thm 6.16 – A trapezoid is isosceles iff its diagonals are congruent.B C A D
If , then Trapezoid ABCD is isosceles.

5. Ex 2: Given isosceles trapezoid PQRS, find and .
50° P Q
The trapezoid is isosceles, so base angles are congruent (the measures are equal).
are consecutive, hence supplementary.

6. Ex 2: Given isosceles trapezoid PQRS, find and .
50° P Q
Again, base angles in an isosceles trap are congruent!

7. Proceed with the PowerPoint when finished.
Recall, the midsegment of a triangle joins the midpoints of the sides. For a trapezoid, it joins the midpoints of the trapezoid’s legs.
midsegment
Click on the link. Read up to the formula to determine the length of a trapezoid’s midsegment:
Proceed with the PowerPoint when finished.

8. Ex 3: Find the length of midsegment .A B M P
20m

9. C B A F 8 D E 9 x
Ex 4: Find x.
Multiply both sides by 2 to get rid of the fraction

10. *ask for your handout on 6.5 once you’ve gotten to this slide
Assignment
Page 359 #10 – 24
*ask for your handout on 6.5 once you’ve gotten to this slide