# Geometry

The flashcards below were created by user duhhitsjessie on FreezingBlue Flashcards.

1. How to prove a quadrilateral a parallelogram.
• 1. Prove both pairs of opposite sides congruent. [distance formula 4x]
• 2. Prove both pairs of opposite sides are parallel [slope formula 4x]
• 3. Prove one pair of opposite sides are both parallel and congruent [distance formua 2x, slope formula 2x]
• 4. Prove diagonals bisect each other. If both diagonals have the same midpoint, they bisect eachother. [midpoint formula 2x]
2. How to prove a quadrilateral is a rectangle.
• FIRST: Prove the quadrilateral is a parallelogram.
• THEN:
• 1. Prove the diagonals are congruent [distance formula 2x]
• 2. Prove there is a right angle. [slope formula 2x, show that two adjacent sides have negative reciprocal slopes]
3. How to prove a quadrilateral is a rhombus.
• 1. Prove all sides are congruent. [distance formula 4x- easiest way]
• *doing this proves it is a parallelogram & a rhombus at the same time
• 2. Prove it is a parallelogram with a pair of adjacent sides congruent [distance formula]
• 3. Prove it is a parallelogram with diagonals perpendicular to eachother [slope formula]
4. How to prove a quadrilateral is a square.
• 1. Prove it is a rectangle with a pair of adjacent sides congruent. [distance formua 4x]
• *to prove it is a rectangle, you have to prove it is a parallelogram first*
• 2. Prove it is a rectangle with the diagonals perpendicular to eachother. [slope formula 2x]
• 3. Prove it is a rectangle with a pair of adjacent sides that are perpindicular [slope formula 2x]
5. How to prove a quadrilateral is a trapezoid.
• 1. Prove that one pair of opposite sides are parallel. [slope formua 2 times]
• AND
• 2. Prove that one pair of opposite sides are NOT parallel. [slope formula 2x]
 Author: duhhitsjessie ID: 22395 Card Set: Geometry Updated: 2010-06-07 02:59:22 Tags: Coordinate Geometry Proofs Folders: Description: Coordinate Geometry Show Answers: