6.6: Chapter 6 Review
Keywords and Theorems
 Polygon Sum Formula

For any
n− gon, the sum of the interior angles is(n−2)×180∘ .
 Equiangular Polygon Formula

For any equiangular
n− gon, the measure of each angle is(n−2)×180∘n .
 Regular Polygon
 When a polygon is equilateral and equiangular.
 Exterior Angle Sum Theorem

The sum of the exterior angles of any polygon is
360∘ .
 Parallelogram
 A quadrilateral with two pairs of parallel sides.
 Opposite Sides Theorem
 If a quadrilateral is a parallelogram, then the opposite sides are congruent.
 Opposite Angles Theorem
 If a quadrilateral is a parallelogram, then the opposite angles are congruent.
 Consecutive Angles Theorem
 If a quadrilateral is a parallelogram, then the consecutive angles are supplementary.
 Parallelogram Diagonals Theorem
 If a quadrilateral is a parallelogram, then the diagonals bisect each other.
 Opposite Sides Theorem Converse
 If the opposite sides of a quadrilateral are congruent, then the figure is a parallelogram.
 Opposite Angles Theorem Converse
 If the opposite angles of a quadrilateral are congruent, then the figure is a parallelogram.
 Consecutive Angles Theorem Converse
 If the consecutive angles of a quadrilateral are supplementary, then the figure is a parallelogram.
 Parallelogram Diagonals Theorem Converse
 If the diagonals of a quadrilateral bisect each other, then the figure is a parallelogram.
 Theorem 610
 Rectangle Theorem
 A quadrilateral is a rectangle if and only if it has four right (congruent) angles.
 Rhombus Theorem
 A quadrilateral is a rhombus if and only if it has four congruent sides.
 Square Theorem
 A quadrilateral is a square if and only if it has four right angles and four congruent sides.
 Theorem 614
 A parallelogram is a rectangle if and only if the diagonals are congruent.
 Theorem 615
 A parallelogram is a rhombus if and only if the diagonals are perpendicular.
 Theorem 616
 A parallelogram is a rhombus if and only if the diagonals bisect each angle.
 Trapezoid
 A quadrilateral with exactly one pair of parallel sides.
 Isosceles Trapezoid
 A trapezoid where the nonparallel sides are congruent.
 Theorem 617
 The base angles of an isosceles trapezoid are congruent.
 Theorem 617 Converse
 If a trapezoid has congruent base angles, then it is an isosceles trapezoid.
 Isosceles Trapezoid Diagonals Theorem
 The diagonals of an isosceles trapezoid are congruent.
 Midsegment (of a trapezoid)
 A line segment that connects the midpoints of the nonparallel sides.
 Midsegment Theorem
 The length of the midsegment of a trapezoid is the average of the lengths of the bases
 Kite
 A quadrilateral with two sets of adjacent congruent sides.
 Theorem 621
 The nonvertex angles of a kite are congruent.
 Theorem 622
 The diagonal through the vertex angles is the angle bisector for both angles.
 Kite Diagonals Theorem
 The diagonals of a kite are perpendicular.
Quadrilateral Flow Chart
Fill in the flow chart according to what you know about the quadrilaterals we have learned in this chapter.
Sometimes, Always, Never
Determine if the following statements are sometimes, always or never true.
 A trapezoid is a kite.
 A square is a parallelogram.
 An isosceles trapezoid is a quadrilateral.
 A rhombus is a square.
 A parallelogram is a square.
 A square is a kite.
 A square is a rectangle.
 A quadrilateral is a rhombus.
Table Summary
Determine if each quadrilateral has the given properties. If so, write yes or state how many sides (or angles) are congruent, parallel, or perpendicular.
Opposite sides 
Diagonals bisect each other 
Diagonals 
Opposite sides 
Opposite angles 
Consecutive Angles add up to 


Trapezoid  
Isosceles Trapezoid  
Kite  
Parallelogram  
Rectangle  
Rhombus  
Square 
Find the measure of all the lettered angles below. The bottom angle in the pentagon (at the bottom of the drawing) is
Texas Instruments Resources
In the CK12 Texas Instruments Geometry FlexBook, there are graphing calculator activities designed to supplement the objectives for some of the lessons in this chapter. See http://www.ck12.org/flexr/chapter/9691.
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