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RECTANGLES. Recognize and apply properties of rectangles. Determine whether parallelograms are rectangles. Parts of the tennis court are marked by parallel and perpendicular lines. PROPERTIES OF RECTANGLES. A rectangle is a quadrilateral with four right angles.
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RECTANGLES • Recognize and apply properties of rectangles. • Determine whether parallelograms are rectangles. Parts of the tennis court are marked by parallel and perpendicular lines.
PROPERTIES OF RECTANGLES A rectangle is a quadrilateral with four right angles. Since both pairs of opposite angles are congruent, it follows that a rectangle is a special type of parallelogram.
THEOREM DIAGONALS OF A RECTANGLE If a parallelogram is a rectangle, then the diagonals are congruent. A B D C
Key ConceptRectangles Properties A B Opposite sides are congruent and parallel D C
Key ConceptRectangles Properties A B Opposite sides are congruent and parallel Opposite angles are congruent D C
Key ConceptRectangles Properties A B Opposite sides are congruent and parallel Opposite angles are congruent Consecutive angles are supplementary D C
Key ConceptRectangles Properties A B Opposite sides are congruent and parallel Opposite angles are congruent Consecutive angles are supplementary Diagonals are congruent and bisect each other. D C
Key ConceptRectangles Properties A B Opposite sides are congruent and parallel Opposite angles are congruent Consecutive angles are supplementary Diagonals are congruent and bisect each other. All four angles are right angles. D C
Example 1Diagonals of a Rectangle P O MNOP is a rectangle MO is 6x + 14, PN is 9x + 5 Find x M N
Example 1Diagonals of a Rectangle P O MNOP is a rectangle MO is 6x + 14, PN is 9x + 5 Find x M N Solution: Diagonals of a rectangle are congruent Subtract 6x from each side Subtract 5 from each side Divide each side by 3
Example 2Angles of a Rectangle (4x + 5)° A D Find x (9x + 20)° B C
Example 2Angles of a Rectangle (4x + 5)° A D Find x (9x + 20)° B C Solution: Angle addition theorem Simplify Subtract 25 from each side Divide each side by 13
PROVE THAT PARALLELOGRAMS ARE RECTANGLES THEOREM If the diagonals of a parallelogram are congruent, then the parallelogram is a rectangle A B D C
Example 3Rectangle on a Coordinate Plane Quadrilateral F(-4, -1), G(-2, -5), H(4, -2), J(2, 2) Determine whether FGHI is a rectangle. J 2 1 -4 -2 2 4 F -1 H -2 -3 -4 -5 G