When you reach this contradiction state that your assumption is false and therefore the prove statement must be true. In this section we will learn 7 methods for proving lines parallel but in order to prove the first of these theorems we will need two other geometric theorems. Parts Theorem - The whole is greater than each of its parts. This theorem is used whenever you want to state a segment or angle is greater than the parts that add up to it. 5.4 Polygon A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others.
Diagonals are any segments in a polygon that connect non adjacent vertices.
Rhombus - parallelogram with 4 congruent sides Square is a parallelogram with 4 congruent sides and 4 congruent angles Trapezoid is a quadrilateral with exactly one pair of sides parallel. The parallel sides are referred to as bases The non parallel sides are referred to as legs. 5.6 Methods of proving a quadrilateral is a parallelogra 5 methods of proving a quadrilateral is a parallelogram 1. Prove both pair of opposite sides congruent. Prove both pair of opposite angles congruent.