## 18 terms

### trapezoid

a quadrilateral with exactly one pair or parallel sides and legs not congruent
NOT A PARALLELOGRAM

### rhombus

a parallelogram with at least two consecutive sides congruent

all 4 sides are congruent
opposite sides are parallel
opposite angles are congruent
diagonals bisect each other
any pair of consecutive angles are supplementary

### parallelogram

a quadrilateral in which both pairs of opposite sides are parallel

opposite sides are parallel
opposite sides are congruent
opposite angles are congruent
diagonals bisect each other
any pair of consecutive angles are supplementary

a four-sided polygon in which the angles sum to 360 degrees

### isosceles trapezoid

a trapezoid in which the nonparallel sides are congruent

the legs are congruent by definition
the bases are parallel (by def. of trapezoid)
the lower base angles are congruent
the upper base angles are congruent
the diagonals are congruent
any lower base angle is supplementary to any upper base angle

### kite

a quadrilateral in which two non-consecutive pairs of consecutive sides are congruent

opposite sides are NOT congruent
two pairs of consecutive sides are congruent
the diagonals are perpendicular to each other
one diagonal is the perpendicular bisector of the other
one of the diagonals bisects a pair of opposite angles
one pair of opposite angles are congruent

### square

a parallelogram that is both a rectangle and a rhombus

opposite sides are parallel
opposite sides are congruent
opposite angles are congruent
diagonals bisect each other
any pair of consecutive angles are supplementary
all 4 sides are congruent
opposite sides are parallel
opposite angles are congruent
diagonals bisect each other
any pair of consecutive angles are supplementary
All angles are right angles
the diagonals are congruent and also bisect each other

### rectangle

a parallelogram with at least one right angle

opposite sides are parallel
opposite sides are congruent
opposite angles are congruent
diagonals bisect each other
any pair of consecutive angles are supplementary
All angles are right angles
the diagonals are congruent. They also bisect each other

### A quadrilateral is a Rectangle if:

the parallelogram contains at least 1 right angle
diagonals are congruent
All 4 angles are right angles

### A quadrilateral is a Kite if:

2 disjoint pairs are congruent
1 of the diagonals is the perpendicular bisector of the other bisector

### A quadrilateral is a rhombus if:

if a parallelogram has a pair of consecutive sides that are congruent
if a diagonal bisects 2 angles of the parallelogram
if diagonals of the quadrilateral are perpendicular bisectors of each other

### A quadrilateral is a square if:

it is both a rectangle and a rhombus

### A trapezoid is isosceles if: (NOT A PARALLELOGRAM)

non - parallel sides are congruent
if lower or upper base angles are congruent
if diagonals of a trapezoid are congruent

### 5 Ways to Prove a quadrilateral a parallelogram:

1. both pairs of opposite sides parallel
2. both pairs of opposite sides congruent
3. both pairs of opposite angles congruent
4. 1 pair of opposite sides both parallel and congruent
5. diagonals bisect each other

### Convex Polygon

each interior angle is less than 180 degrees

### Concave Polygon

has an interior angle greater than 180 degrees

### Diagonal

a segment that connects 2 non - consecutive vertices of the polygon

### Polygon

a closed - plane figure formed by line segments