1. 6.4 Rhombuses, Rectangles and Squares Pg 347

2. Special Parallelograms Rhombus- a ||’ogram with 4  sides Rectangle- a ||’ogram with 4 rt  s. Square- a ||’ogram with 4  sides and 4 rt  s

3. So far: (we’ll add more later) Quadrilaterals _ _ parallelograms _ rhombus rectangle _ _ square

4. Example sometimes, always, never A rhombus is a rectangle. Sometimes, if it is also a square A parallelogram is a rectangle. Sometimes, if is has 4 rt  ‘s A square is a rhombus. Always A rectangle is a square. Sometimes, if it has 4  sides

5. Corollaries Rhombus corollary- a quad is a rhombus iff it has 4  sides. Rectangle corollary- a quad is a rectangle iff it has 4 rt  ‘s Square corollary- a quad is a square iff it is a rhombus and a rectangle.

6. Thm 6.11 A parallelogram is a rhombus iff its diagonals are . J K LM _ _ _ _ If seg JL  seg KM, then JKLM is a rhombus. If JKLM is a rhombus, then seg JL  seg KM

7. Thm 6.12 A ||ogram is a rhombus iff each diagonal bisects a pair of opposite  s. A B C D ) ) ( ( )) ((

8. Thm 6.13 A ||’ogram is a rect  if its diagonals are  Q R S T If QRST is a rectangle then seg QS  seg RT If seg QS  seg RT then QRST is a rectangle.