Then: You determined whether quadrilaterals were parallelograms and/or rectangles. Now: 1. Recognize and apply the properties of rhombi and squares. 2. Determine whether quadrilaterals are rectangles, rhombi, or squares. 6.5 RHOMBI AND SQUARES ges/rhombus/baseball-diamond-as-rhombus.gif
Parallelogram with all four sides congruent. *All the properties of a parallelogram RHOMBI
DIAGONALS OF A RHOMBUS
Theorem 6.16 If a parallelogram is a rhombus, then each diagonal bisect a pair of opposite angles. If ABCD is a rhombus, then DCA BCA DAC BAC DIAGONALS OF A RHOMBUS
The diagonals of rhombus WXYZ intersect at V. Use the given information to find each measure or value. a. If m WZX = 39.5, find m ZYX. b. If WX = 12 and VX = 5, find WV. c. If m WZX = 41, find m YWZ. EXAMPLE 1: USE PROPERTIES OF A RHOMBUS
d. If WX = 8x – 5 and WZ = 6x + 3, find x. e. If m ZWY = 6y + 7 and m XYW = 9y -5, find y. EXAMPLE 1:
Parallelograms with four congruent sides and four congruent angles. Parallelogram that is both a rectangle and a rhombus is a square. SQUARES
EFGH is a square. If GJ = 15, find each measure. a. m EJF = b. m JFG = c. FH = d. EJ = e. EF = SQUARES
CONCEPT SUMMARY: PARALLELOGRAMS
CONDITIONS FOR RHOMBI AND SQUARES
Theorem 6.18 If one diagonal of a parallelogram bisects a pair of opposite angles, then the parallelogram is a rhombus. If 1 2 and 3 4,or 5 6 and 7 8, then ABCD is a rhombus. CONDITIONS FOR RHOMBI AND SQUARES
Theorem 6.20 If a quadrilateral is both a rectangle and a rhombus, then it is a square. CONDITIONS FOR RHOMBI AND SQUARES SqRectRhom.jpg
GARDENING Hector is measuring the boundary of a new garden. He wants the garden to be square. He has set each of the corner stakes 6 feet apart. What does Hector need to know to make sure that the garden is square? EXAMPLE 2: USING PROPERTIES OF RHOMBI AND SQUARES
Determine whether parallelogram ABCD is a rhombus, a rectangle, or a square for A(–2, –1), B(–1, 3), C(3, 2), and D(2, –2). List all that apply. Explain. Step 1: The figure looks like _________________ EXAMPLE 4: CLASSIFY QUADRILATERALS USING COORDINATE GEOMETRY
Step 2: Are the diagonals congruent? Step 3: Are the diagonals perpendicular? EXAMPLE 4:
p #7-12 all, 14, evens, all, 44 Handout #14 – proof and #20 & 22 - graphs 6.5 ASSIGNMENT: