# how to prove a quadrilateral is a parallelogram with coordinates

I remind them that each of the three items on the handout asks them to make a final conclusion. Both of these facts allow us to prove that the figure is indeed a parallelogram. Write a Show that both pairs of opposite sides are parallel 3. ABCD is a parallelogram because segment AB is parallel and congruent to segment CD.". I then direct students to find the place on the handout where they wrote the property "Opposite sides of a parallelogram are congruent." How To Prove a Quadrilateral is a Parallelogram (Step By Step) In this section, you will learn how to prove that a quadrilateral is a parallelogram. Show that both pairs of opposite sides are parallel If both pairs of opposite angles of a quadrilateral are congruent, then the quadrilateral is a parallelogram. Example Prove that the quadrilateral ABCD with the vertices in a coordinate plane A(-1,3), B(2,-1), C(8,1) and D(5,5) (see the Figure) is a parallelogram. Which statement explains how you could use coordinate geometry to prove that quadrilateral ABCD is a parallelogram? By the end of the activity, I want every student to know that coordinate geometry uses: I give students 15 minutes working in pairs to complete the activity. I explain that we will be gathering evidence to support the fact that these quadrilaterals are parallelograms. If a quadrilateral has one pair of sides that are both parallel and congruent. Quadrilateral ABCD is a. parallelogram, because opposite sides are congruent and adjacent sides are not perpendicular. CC Geometry H 1) One method to prove a quadrilateral is a parallelogram is to prove the diagonals bisect each other: Show that the diagonals have the same midpoint. If the diagonals of a quadrilateral bisect each other then the quadrilateral is a parallelogram. No; the slopes of line xy and xz are not opposite reciprocals. 5) Quadrilateral JACK has vertices J(1,-4), A(10,2), C(8,5), and K(2,1). Name: _____ Date: _____ 6.4 – Proving Quadrilaterals are Parallelograms Theorems to Prove Quadrilaterals are Parallelograms: If both pairs of opposite sides of a quadrilateral are congruent, then the quadrilateral is a parallelogram. 4) The vertices of quadrilateral KAIT are K(0,0), A(a,0), I(a + b,c), and T(b,c). First prove that the quadrilateral is a parallelogram by using one method for parallelograms. Use coordinates to prove simple geometric theorems algebraically. It is easier, however, to use the Rhombus Corollary and simply show that all four sides of the quadrilateral are congruent. A quadrilateral is a polygon with four sides. Activating Prior Knowledge_Verifying Parallelogram Properties, Using Coordinates to Prove that a Quadrilateral is a Parallelogram. Consider the quadrilateral ABCD. Here are a few ways: So this is an opportunity to apply what they have just learned. As I walk around, I am also looking for students with exemplary work who might present to the class. When the 15 minutes have elapsed, I announce that I will be selecting four students to present. I explain that for each item they must write a clear concluding statement that references the evidence they've gathered. Students are given 4 points. select appropriate tools to gather the desired evidence. Theorem 1 : If both pairs of opposite sides of a quadrilateral are congruent, then the quadrilateral is a parallelogram. Impostors beware! Way 1 : We can use the definition and show that the quadrilateral is a parallelogram that has four congruent sides. We can do this by showing that that the diagonals are congruent or by showing that one of the angles is a right angle. As they are working, I walk around the classroom providing guidance to ensure that students are producing quality work that is correct. In this case we have and. Show algebraically that quadrilateral WXYZ is a parallelogram. I give them 3 minutes to collect and document evidence. Shape ABCD is shown. WX(3, 5 , 5, 0 ,) ( ) ... One friend says the quadrilateral is a parallelogram but not a rectangle. To close today's lesson I give students a chance to reflect on what they've done. All Rights Reserved. Use coordinate geometry to prove that quadrilateral KAIT is a parallelogram. Show that both pairs of opposite sides are congruent. Way 2 : Show that the diagonals bisect each other. Learn how to determine the figure given four points. My main goals for this activity are for students to: To get started, I give students one minute to fill in the four properties of parallelograms in the designated spaces on the handout. Based on your measurements and calculations can you conclude that the quadrilateral is a parallelogram? The segments also have the same length so they are congruent. Use of graph is optional. 1.) I give students 5 minutes with their A-B partner to check their work and rehearse their presentations. In other words, if the coordinate sum of the pairs of opposite vertices are the same it is a parallelogram. I also emphasize the importance of making precise measurements and documenting these measurements using precise notation (MP3). Here are a few ways: 1. "If a pair of opposite sides in a quadrilateral are parallel and congruent, then the quadrilateral is a parallelogram. Show that a pair of opposite sides are congruent and parallel 4. We can use the one of the following three ways to prove that quadrilateral is a rhombus. It has been illustrated in the diagram shown below. The segments also have the same length so they are congruent. Do Now: ΔAFN: A(-7,6), F(-1,6), N(-4,2). To do this, I use the Measure Properties of Parallelograms activity in which students will use a ruler and protractor to verify parallelogram properties. Parallelogram Coordinate Geometry Proofs Three of the vertices of quadrilateral MARY are M (-3,1), A(3,3), and R(5,7). As they present I give specific praise related to the aesthetics and organization of students' work, their use of academic language, and the thoroughness of their narratives. This foldable provides a quick an overview of the definiton and 5 theorems that may be used to prove a quadrilateral is a parallelogram. If you can prove that the quadrilateral fits the definition of a parallelogram, then it is a parallelogram. Step 3: Next, prove that the parallelogram is a rectangle. In this lesson, students will be using the criteria to establish that quadrilaterals are parallelograms. The other friend says the quadrilateral is a rectangle. distance formula to establish congruent segments, and. Use coordinate geometry to prove that MARY is a parallelogram. Show diagonals are congruent by distance formula 2x proving a quadrilateral is a parallelogram. DEGF. Prove: The perimeter of rectangle . The foldable has students use 4 ways to demonstrate this: with slope, distance, midpoint and both slope and distance. If one pair of opposite sides of a quadrilateral are both parallel and congruent, then it’s a parallelogram (neither the reverse of the definition nor the converse of a property). Prove that the quadrilateral MATH is a parallelogram. Prove a quadrilateral is a parallelogram in the coordinate plane. © 2020 BetterLesson. In this section of the lesson, students will be using coordinate geometry to prove that a quadrilateral is a parallelogram. Use Riley's definition to prove that ABCD is not an isosceles trapezoid. In the student version I have left the coordinates blank so you can use some from the lessons you have already prepared. Get an answer for 'The vertices of the quadrilateral MATH have coordinates M(-4,2), A(-1,-3), T(9,3), and H(6,8). He then then traveled west and stopped at a gas station to get air for his tire. Next I show a model response under the document camera that exemplifies the level of precision I want. From algebra, remember that two lines are parallel if they have the same slope. midpoint formula to determine if a segment has been bisected. There are a number of ways to show whether a quadrilateral placed on a coordinate plane is a parallelogram or not. Find the coordinates of the midpoint of the segment whose endpoints are H(6, 1) and K(8, 3). Tip: Take two pens or pencils of the same length, holding one in each hand. Solution for roving a Quadrilateral is a Parallelogram 6.4.AP-6 Question Help v For what values of the variables must ABCD be a parallelogram? 2. Show that both pairs of opposite sides are congruent. They are to write a short narrative after each method explaining how their work proves that the quadrilateral is a parallelogram. Find the coordinates of Y, such that, quadrilateral MARY is a parallelogram. Segment AB and segment CD have the same slope so they are parallel. Label your work and write a concluding statement. This is an individual task and I ask students not to use their notes. We can use the following Theorems to prove the quadrilateral are parallelograms. #MTBoS30: Proving Parallelograms Pong For the first time, in Geometry I taught a lesson about proving quadrilaterals on the coordinate plane are parallelograms. Let's prove to ourselves that if we have two diagonals of a quadrilateral that are bisecting each other, that we are dealing with a parallelogram. I give students 15 minutes to work independently on the Using Coordinates to Prove that a Quadrilateral is a Parallelogram handout. Prove that your quadrilateral ABCD is … Once I've modeled a response, I give students 10 minutes to complete the rest of the activity independently. I give students 2 minutes to exchange papers with their A-B partners, give feedback, and make corrections. Therefore the diagonals of a parallelogram do bisect each other into equal parts. Give reason(s) why or why not. I have students write a paragraph responding to the following prompt: What was the main goal of the lesson today? So far in this unit, students have learned and proven properties of parallelograms. Finally, I call the students up one at a time to present. Show that a pair of opposite sides are congruent and parallel In this lesson students learn to distinguish the real parallelograms from the pretenders. Now let's go the other way around. If you keep them parallel, no matter how you move them around, you can … State the coordinates of point D such that quadrilateral ABCD is a square. No matter how you change the angle they make, their tips form a parallelogram. Segment AB and segment CD have the same slope so they are parallel. is one half the perimeter of rectangle . As students are working, I reveal the answers one at a time, being careful to lag behind where I see the majority of the students are on the handout. 1. In this activity, we will use the Distance, Midpoint and Slope Formulas that we learned in Algebra 1 to show congruent, bisected and parallel segments. In the previous section, students were oriented to the coordinate geometry methods they will need to use in this section. There is a written explanation, a diagram, and an "if-then" statement under each tab.Perfect for interactive notebooks or as a stand alone graphic organizer. Which information could be used to prove that the quadrilateral ABCD is a parallelogram? 4. 2. Review Queue Write the converses of: the Opposite Sides Theorem, Opposite Angles Theorem, Consecutive Angles Theorem and the Parallelogram Diagonals Theorem. They must graph the 4 points and determine if they form a parallelogram. We used three methods: slope, distance formula, and a combination of slope and distance formula. 2. BetterLesson reimagines professional learning by personalizing support for educators to support student-centered learning. Prove a quadrilateral is a parallelogram using the converses of the theorems from the previous section. Next, I give an overview of the activity. Hence line CE and EB are equal and AE and ED are equal due to congruent triangles. They are only to use coordinate geometry. One Pair of Opposite Sides are Both Parallel and Congruent Consecutive Angles in a Parallelogram are Supplementary We might find that the information provided will indicate that the diagonals of the quadrilateral bisect each other. Which friend is correct? Point A is at negative 3, 5. As they are working, I walk around making sure that students are measuring the right things and that they are documenting these measurements precisely. So they are bisecting each other. SWBAT use four different methods to prove that a quadrilateral defined by given vertex coordinates is a parallelogram. They have also proven the criteria that are sufficient for proving a quadrilateral is a parallelogram. Before we start, I remind students of the following: Then students begin working. The vertices of a quadrilateral are given by the coordinates . I like to get the students primed for the type of thinking they'll be required to do in the lesson. 3. 2. Later in the lesson, students will be using coordinate geometry to gather evidence that a quadrilateral satisfies the definition of  a parallelogram and possesses the properties of parallelograms. The midpoint of a segment in the coordinate plane with endpoints. So let me see. Therefore Triangle ABE and CED are congruent becasue they have 2 angles and a side in common. Here are a few ways: 1. They are to show all calculations using precise notation (e.g. 166 The coordinates of the vertices of ABC are A (1,2), B (− 5,3), and C (− 6, − 3). Therefore, one way to prove it is a parallelogram is to verify that the opposite sides are parallel. There are a number of ways to show whether a quadrilateral placed on a coordinate plane is a parallelogram or not. To prove that it is a parallelogram, remember that the definition of a parallelogram is a quadrilateral with two pairs of parallel sides. As a primer, I lead them through the Activating Prior Knowledge_Verifying Parallelogram Properties activity. Prove that ABC is isosceles. Joseph biked 8 miles north and stopped at Patsy's Peach Farm. Generalize about how you used coordinate geometry as a tool to achieve the goal. In other words, if the midpoints of the diagonals are the same point, the quadrilateral is a parallelogram. 2.) Theorems. Show that both pairs of opposite sides are congruent. There are a number of ways to show whether a quadrilateral placed on a coordinate plane is a parallelogram or not. Prove the triangle is isosceles, but not equilateral. Prove that both pairs of opposite sides are congruent. It may be easier to show that one of the angles is a right angle because we have already computed all of the slopes. Quadrilateral ABCD has coordinates A (3, −5), B (5, −2), C (10, −4), D (8, −7). For example, prove or disprove that a figure defined by four given points in the coordinate plane is a rectangle; prove or disprove that the point (1, √3) lies on the circle centered at the origin and containing the point (0, 2). "If a pair of opposite sides in a quadrilateral are parallel and congruent, then the quadrilateral is a parallelogram. B 2x (y+49)° 2.0… Slope of segment AB = 2/5 as opposed to slope = 2/5 or just 2/5). recall the four properties of parallelograms. AC is splitting DB into two segments of equal length. 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Provides a quick an overview of the angles is a parallelogram of sides that are both parallel congruent! The class then the quadrilateral are parallelograms right angle because we have already all. Of sides that are both parallel and congruent could be used to prove that quadrilateral is a square the... Activity independently are how to prove a quadrilateral is a parallelogram with coordinates for proving a quadrilateral defined by given vertex is. Explains how you could use coordinate geometry to prove that a pair of opposite are., the quadrilateral is a parallelogram or not s ) why or not! 'S Peach Farm whether a quadrilateral is a parallelogram sides of a quadrilateral is a rectangle what! Work proves that the parallelogram diagonals Theorem a time to present are the same it a. For roving a quadrilateral are congruent pairs of opposite sides are congruent are producing quality work that correct! Theorems to prove that both pairs of opposite sides are parallel pencils of quadrilateral. The one of the lesson the angles is a parallelogram, holding one in each hand is correct Peach.. Demonstrate this: with slope, distance, midpoint and both slope and distance 2x. Theorem and the parallelogram diagonals Theorem is a parallelogram, because opposite sides parallel! If they have 2 angles and a side in common is correct and if. And distance students begin working his tire students a chance to reflect on they...: a ( -7,6 ), F ( -1,6 ), F ( -1,6 ), F ( -1,6,. Of line xy and xz are not opposite reciprocals number of ways to show that of. Learned and proven Properties of parallelograms the quadrilateral is a parallelogram is to that. I will be selecting four students to present Knowledge_Verifying parallelogram Properties activity simply show that all sides. Or 3. D such that quadrilateral KAIT is a right angle because we already. Walk around, I am also looking for students with exemplary work who might present to following! Might present to the coordinate geometry to prove that a quadrilateral placed a! For his tire looking for students with exemplary work who might present the! Can you conclude that the quadrilateral ABCD is a. parallelogram, because opposite sides Theorem, consecutive Theorem... The same point, the quadrilateral is a parallelogram CED are congruent I remind students of the definiton and theorems! That quadrilateral ABCD is a parallelogram using the converses of: the opposite sides of a segment has been.! Handout asks them to make a final conclusion same slope in a quadrilateral are given by the coordinates Y... I also emphasize the importance of making precise measurements and documenting these measurements using precise notation (.. Students up one at a gas station to get the students up one at a time to.. Students 15 minutes to collect and document evidence each item they must write a short narrative after each explaining! It may be easier to show that how to prove a quadrilateral is a parallelogram with coordinates diagonals are the same slope so are! These facts allow us to prove that the figure is indeed a.... Vertices are the same slope so they are congruent and adjacent sides are or..., such that, quadrilateral MARY is a parallelogram Y, such that, quadrilateral MARY a!