Geometry Unit 8 Vocabulary
Quadrilaterals
Bisect- Cut into two congruent halves.
Ex. Segment and angle bisectors
Consecutive sides and/or angles
Consecutive Angles - Two angles whose vertices are the endpoints of the same side are called consecutive
angles.
Consecutive Sides - Two sides of a quadrilateral that meet are called consecutive sides.
QR and RS are consecutive sides because they meet at point R.
Concave - (of a polygon) having at least one interior angle greater than 180°.
a. Convex - (of a polygon) having all interior angles less than or equal to 180°.
Diagonals - a line segment linking two non-adjacent vertices.
Exterior Angles - the angle between any side of a shape, and a line extended from the next side
Interior Angles - the angle inside the shape.
Isosceles trapezoid – a trapezoid is isosceles if and only if it has a pair of base angles equal in measure
Properties –
 Bases parallel
 Legs congruent
 Lower base angles are congruent.
 Upper base angles are congruent.
 Any lower base angle is supplementary to any upper base angle.
 Diagonals are congruent
Kite –a quadrilateral is a kite if and only if it has two distinct pairs of consecutive sides of the same length
Properties –
 Two disjoint pairs of consecutive sides are congruent. (Note:
Disjoint means that the two pairs are totally separate.)
 Diagonals are perpendicular.
 One diagonal is the perpendicular bisector of the other diagonal
 One diagonal bisects a pair of opposite angles
 The opposite angles at the endpoints of the cross diagonal are
congruent
Opposite Angles - Two angles that are not consecutive are called opposite angles.
Opposite Sides - Two sides that are not consecutive are called opposite sides.
QR and TS are opposite sides of the quadrilateral because they do not meet.
Parallelogram - a quadrilateral is a parallelogram if and only if both pairs of its opposite sides are parallel.
Properties –
 Opposite sides are parallel
 Opposite sides are congruent
 Opposite angles are congruent
 Consecutive angles are supplementary
 The diagonals bisect each other
Polygon- a number of coplanar line segments, each connected end to end to form a closed shape
Quadrilateral – a closed figure with four sides and four angles
Rectangle – a quadrilateral is a rectangle if and only if it has four right angles
Properties –
 Opposite sides parallel
 Opposite side congruent
 All right angles
 Congruent diagonals
 Diagonals bisect each other
Rhombus - a quadrilateral is a rhombus if and only if its four sides are equal in length
Properties –
 Opposite sides parallel
 All sides congruent
 Diagonals bisect each other
 Consecutive angles supplementary
 Diagonals are perpendicular
 Diagonals bisect angles
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Square – a quadrilateral is a square if and only if it has four equal sides and four right angles
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Properties –
 Opposite sides parallel
 All sides congruent
 Diagonals bisect each other
 Consecutive angles supplementary
 Diagonals are perpendicular
 Diagonals bisect angles
 Diagonals are congruent
Trapezoid – a quadrilateral is a trapezoid if and only if it has at least one pair of parallel sides