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Section 5.5. Properties of Quadrilaterals. Properties of Parallelograms. Opposite sides are parallel ( DC ll AB, AD ll BC ) Opposite sides are congruent ( DA CB, DC AB ) Opposite angles are congruent (<DAB <DCB, <ABC <ADC)
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Section 5.5 Properties of Quadrilaterals
Properties of Parallelograms • Opposite sides are parallel ( DC ll AB, AD ll BC ) • Opposite sides are congruent ( DA CB, DC AB ) • Opposite angles are congruent (<DAB <DCB, <ABC <ADC) • Diagonals bisect each other (DB bis. AC, AC bis. DB) • Consecutive angles are supplementary(<DAB suppl. <ADC, etc.) • Diagonals form 2 congruent triangles ( ABC CDA, DCB BAD)
Properties of A Rectangle • All properties of a parallelogram apply • All angles are right angles and . • Diagonals are ( ) B A C D
Properties of a kite • Two disjoint pairs of consecutive sides are • Diagonals are • One diagonal is the bisector of the other • One of the diagonals bisect a pair of opposite <‘s • One pair of opposite <‘s are A D B C
Properties of a Rhombus • Parallelogram Properties • Kite Properties • All sides are congruent • Diagonals bisect the angles • Diagonals are perpendicular bisectorsof each other • Diagonals divide the rhombus into 4 congruent rt. Triangles
Properties of squares • Rectangle Properties • Rhombus Properties • Diagonals form 4 isos. right triangles
Properties of trapezoids • Exactly one pair of sides parallel
Properties of isosceles trapezoids • Legs are congruent • Bases are parallel • Lower base angles are congruent • Upper base angles are congruent • Diagonals are congruent • Lower base angles are suppl. to upper base angles
Always, sometimes, never The diagonals of a rectangle are congruent Every square is a rectangle Every quadrilateral is a trapezoid In a trap. opp angles are congruent A rhombus is a rectangle An isos. trap is parallelogram Consecutive angles of a square are congruent Rhombuses are parallelograms Squares have only one right angle No trapezoid is a rectangle An isosceles trapezoid has no parallel lines Always Always Sometimes Never Sometimes Never Always Always Never Always Never Practice Problems
C Sample problems Given: Triangle ACE is isos. With base AE CD CB AG FE BD GF Prove: BGFD is a parallelogram B D E A G F Statements Reasons tri. ACE is isos. w/ base AE CD CB AG FE BD GF 1. Given 2. Given 3. Given 4. Given 5. <A <E 5. If isos, then <‘s 6. CA CE 6. If <‘s, then sides 7. BA DE 7. Subtraction 8. Tri. BAG Tri. DEF 8. SAS(3,5,7) 9. BG DF 9. CPCTC 10. BGDF is a parallelogram 10. If opp. sides are then figure is a parallelogram
Sample problem #2 Given: ABCD is a rhombus E Prove: AC is perp. DB
Sample Problem #2 E Statement Reason 1. ABCD is a rhombus 2. AD DC 3. DE DE 4. AE CE 5. Tri. ADE and Tri. CDE 6. <AED <CED 7. <AED and <CED are rt <s 8. AC DB 1. Given 2. In a rhombus opp. Sides are 3. Reflexive 4. In a parallelogram diag. bisect each other 5. SSS(2,3,4) 6. CPCTC 7. If 2 <s are and suppl. They are rt. <s. 8. Rt <s are formed by perp. lines
Works Cited "Quickie Math." Quickie Math , n.d. Web. 19 Jan 2011. <library.thinkquest.org/C006354/11_1.html>. Rhoad, Richard, George Miluaskas, and Robert Whipple. Geometry for Enjoyment and Challenge. New Edition ed. Boston: McDougal Littell, 1997. Print. “Rhombus problems." analyze math. A Dendane , 5 November 2010. Web. 19 Jan 2011. <http://www.analyzemath.com/Geometry/rhombus _problems.html>.