# How do you use coordinate proofs?

Table of Contents

## How do you use coordinate proofs?

When developing a coordinate geometry proof:

- Plot the points, draw the figure and label.
- State the formulas you will be using.
- Show ALL work.
- Have a concluding sentence stating what you have proven and why it is true. Usually a theorem or a definition is needed here.

## How can we use variable coordinates to prove theorems?

The coordinate proof is a proof of a geometric theorem which uses “generalized” points on the Cartesian Plane to make an argument. The method usually involves assigning variables to the coordinates of one or more points, and then using these variables in the midpoint or distance formulas .

## What is a coordinate proof example?

In a coordinate proof, you are proving geometric statements using algebra and the coordinate plane. Some examples of statements you might prove with a coordinate proof are: Prove or disprove that the quadrilateral defined by the points \begin{align*}(2,4),(1,2),(5,1),(4,-1)\end{align*} is a parallelogram.

## How do you prove it’s a square?

- If a quadrilateral has four congruent sides and four right angles, then it’s a square (reverse of the square definition).
- If two consecutive sides of a rectangle are congruent, then it’s a square (neither the reverse of the definition nor the converse of a property).

## How do you prove a rectangle is a coordinate?

Prove it is a Rectangle

- – The opposite sides are parallel and congruent. – The diagonals bisect each other.
- – There are 4 right angles. – The diagonals are congruent.
- A(0, -3), B(-4, 0), C(2, 8), D(6, 5)
- – Show that both pairs of opposite sides are congruent. – Show that both pairs of opposite sides are parallel.

## How do you show that a parallelogram is a rectangle?

If a parallelogram is known to have one right angle, then repeated use of co-interior angles proves that all its angles are right angles. If one angle of a parallelogram is a right angle, then it is a rectangle.

## What is the difference between a direct and indirect proof?

The main difference between the two methods is that direct poofs require showing that the conclusion to be proved is true, while in indirect proofs it suffices to show that all of the alternatives are false. Direct proofs assume a given hypothesis, or any other known statement, and then logically deduces a conclusion.

## What type of proof did you use direct or indirect?

As it turns out, your argument is an example of a direct proof, and Rachel’s argument is an example of an indirect proof. A direct proof assumes that the hypothesis of a conjecture is true, and then uses a series of logical deductions to prove that the conclusion of the conjecture is true.

## What is the indirect proof rule?

ad absurdum argument, known as indirect proof or reductio ad impossibile, is one that proves a proposition by showing that its denial conjoined with other propositions previously proved or accepted leads to a contradiction.

## How do you prove false implications?

Proof by Contradiction

- This method works by assuming your implication is not true, then deriving a contradiction.
- Recall that if p is false then p –> q is always true, thus the only way our implication can be false is if p is true and q is false.

## What is method of proof?

Methods of Proof. Proofs may include axioms, the hypotheses of the theorem to be proved, and previously proved theorems. The rules of inference, which are the means used to draw conclusions from other assertions, tie together the steps of a proof. Fallacies are common forms of incorrect reasoning.

## What is the sequence of statements that demonstrates that a theorem is true?

It consists of a set of assumptions (called axioms) linked by statements of deductive reasoning (known as an argument) to derive the proposition that is being proved (the conclusion). If the initial statement is agreed to be true, the final statement in the proof sequence establishes the truth of the theorem.

## When proving a theorem which comes first?

Typically, the first few rows of your proof will always be the “givens”. In a two-column proof you will use less words than in a paragraph proof, because you are not writing in complete sentences.