1. Then/Now You used properties of parallelograms and determined whether quadrilaterals were parallelograms. Recognize and apply properties of rectangles. Determine whether parallelograms are rectangles.

2. Concept 1

3. Example 2 A.x = 1 B.x = 3 C.x = 5 D.x = 10 Quadrilateral EFGH is a rectangle. If m  FGE = 6x – 5 and m  HFE = 4x – 5, find x.

4. Concept 2

5. Example 4 Rectangles and Coordinate Geometry Quadrilateral JKLM has vertices J(–2, 3), K(1, 4), L(3, –2), and M(0, –3). Determine whether JKLM is a rectangle using the Distance Formula. Step 1Use the Distance Formula to determine whether JKLM is a parallelogram by determining if opposite sides are congruent.

6. Example 4 Rectangles and Coordinate Geometry Since opposite sides of a quadrilateral have the same measure, they are congruent. So, quadrilateral JKLM is a parallelogram.

7. Example 4 Rectangles and Coordinate Geometry Answer:Since the diagonals have the same measure, they are congruent. So JKLM is a rectangle. Step 2Determine whether the diagonals of JKLM are congruent.