Geometry Postulates and Theorems
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Related Thorems Polygon Theorems
The angles that form a linear pair are supplementary. In a polygon with n sides the sum of the angle measures is (n - 2) 180.
Vertical angles are congruent. Exterior Angles of a Regular Polygon
The sum of the measures of the exterior angles of any polygon is 360.
Two lines are perpendicular if and only if
they form congruent adjacent angles.
 
The Triangle Sum Theorem
The sum of the angle measures of a trianlge is 180.
 
   
   
The opposite sides of a parallelogram are congruent.  
The opposite angles of a parallelogram are congruent.  
The diagonals of a parallelogram bisect each other.