Geometry Theorems and Vocab 6-1 to 6-5
Parallelogram
A quadrilateral with both pairs of opposite sides parallel
Equiangular polygon
All = angles
Equilateral polygon
All = sides
Regular polygon
All = sides, all = angles
Consecutive angles
Angles of a polygon that share a side
Theorem 6-15
If a parallelogram has congruent diagonals, then it is a rectangle
Theorem 6-14
If a parallelogram has diagonals bisect the opposite angles, then it is a rhombus
Theorem 6-18
If a parallelogram is a rectangle, then the diagonals are congruent
Theorem 6-16
If a parallelogram is a rhombus, then the diagonals are perpendicular or
Theorem 6-17
If a parallelogram is a rhombus, then the diagonals bisect opposite angles
Theorem 6-4
If a quadrilateral is a parallelogram, then it's consecutive angles are supplementary
Theorem 6-6
If a quadrilateral is a parallelogram, then it's diagonals bisect each other
Theorem 6-5
If a quadrilateral is a parallelogram, then it's opposite angles are congruent
Theorem 6-3
If a quadrilateral is a parallelogram, then it's opposite sides are congruent
Theorem 6-9
If an angle of a quadrilateral is supplementary to both of it consecutive angles, then the quadrilateral is a parallelogram
Theorem 6-10
If both pairs of opposite sides of a quadrilateral are congruent, then the quadrilateral is a parallelogram
Theorem 6-8
If both pairs of opposite sides of a quadrilateral are congruent, then the quadrilateral is a parallelogram
Theorem 6-12
If one pair of opposite sides of a quadrilateral is both congruent and parallel, then the quadrilateral is a parallelogram
Theorem 6-11
If the diagonals of a quadrilateral bisect each other, then the quadrilateral is a parallelogram
Theorem 6-7
If three or more parallel lines cut off congruent segments on one transversal, then they cut off congruent segments on every transversal
Theorem 6-13
It's a parallelogram has diagnose that form right angles, then it is a rhombus
Corollary to the polygon angle-sum theorem
The measure of each interior angle of a regular n-gon is (n-2)180/n
Theorem 6-2: polygon exterior angle-sum theorem
The sum of the measures of the exterior angles of a polygon, one each vertex, is 360
Theorem 6-1: polygon angle-sum theorem
The sum of the measures of the interior angles of an n-gon
