# Cartesian Coordinates in the Plane 2D - 4th Grade & up

 Definition: The Cartesian Coordinate System is the rectangular system of locating points in the plane.   Rule: A point (x,y) is located by finding its horizontal x-coordinate and its vertical y-coordinate.
InterActivities: Plotting Points and Drawing Basic 2D Shapes

Interactivity 1    Interactivity 2    Interactivity 3    Interactivity 4

 1. Click on the New point tool. In the drawing pad, find the point with coordinates (1,1) and then click. Point A should be drawn. Check the coordinates of point A by rolling your mouse over it. 2. Find the coordinates and draw the point B(1,4). Is B above or right of A?   3. Find the coordinates and draw the points C(5,4) and D(5,1). 4. Use the Segment tool and make the rectangle ABCD. 5. What is the width and height of the rectangle ABCD?
 1. Click on the Reset button to clear the drawing pad. 2. Find and draw the points A(5,0), B(1,3) and C(1,0) 3. Use the segment tool to make the triangle ABC. What kind of triangle is ΔABC?   4. From the coordinates, can you find the lengths of \overline {CA} and \overline {CB} ?   5. Using Pythagoras' theorem, what is the length of \overline {AB} ?     To check your work, click on View -> Algebra Window.
 1. Click on the reset button to clear the drawing pad. 2. Click on the Move drawing pad tool and then click and drag on (0,0) to put it in the middle of the drawing pad. 3. Find and draw the points A(-2,-1), B(1,-4) and C(1,1) 4. Use the segment tool to make the triangle ABC. 5. Click on View -> Algebra Window. You should see 3 free points and 3 dependent line segments: a, b and c. 6. Click on the Move tool and click and drag C until ABC is an isosceles triangle. Answers: Isosceles triangle means 2 equal sides so we want two of a, b or c to be the same. Try C=(0,2). Can you find another point? (There are many, many points.)  Another point:
 To clear the drawing pad, click on the Reset button. 1a. Draw A(0,3) and B(4,1). b. Find a point C (there are 2!) to make triangle ABC a right-triangle   c. Connect A, B and C with line segments. d. Use Pythagoras' theorem to check that \overline {AB} is the "correct" length! 2a. Clear your drawing pad. b. Draw A(1,1) and B(4,3). c. Determine and draw the points C and D that make ACBD a rectangle.

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