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The year is 1630. Lying on his back, French mathematician René Descartes, watches a fly crawl across the ceiling. Suddenly, an idea comes to him. He visualizes.

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Presentation on theme: "The year is 1630. Lying on his back, French mathematician René Descartes, watches a fly crawl across the ceiling. Suddenly, an idea comes to him. He visualizes."— Presentation transcript:

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2 The year is Lying on his back, French mathematician René Descartes, watches a fly crawl across the ceiling. Suddenly, an idea comes to him. He visualizes two number lines, intersecting at a 90° angle. He realizes that he can graph the fly's location on a piece of paper. Descartes called the main horizontal line the x-axis and the main vertical line the y-axis. He named the point where they intersect the origin.

3 Descartes represented the fly's location as an ordered pair of numbers. The first number, the x-value, is the horizontal distance along the x-axis, measured from the origin. The second number, the y-value, is the vertical distance along the y-axis, also measured from the origin.

4 The locations in the plane where the x and y values intersect are called coordinates. X-COORDINATE Y-COORDINATE In the image on the right, three points (0, 0), (-2, 5), and (3, -6.5) are represented as graphed coordinates. ORIGIN

5 The plane containing these points is called the Cartesian plane (in honor of Descartes), or the coordinate plane. Together, the x-axis, the y-axis, the coordinate plane, and all the coordinates make up the Cartesian coordinate system. CARTESIAN COORDINATE SYSTEM

6 The plane determined by a horizontal number line, called the x-axis, and a vertical number line, called the y-axis, intersecting at a point called the origin. Each point in the coordinate plane can be specified by an ordered pair of numbers. COORDINATE PLANE The point (0, 0) on a coordinate plane, where the x-axis and the y-axis intersect. ORIGIN

7 X-COORDINATE Y-COORDINATE ORIGIN CARTESIAN COORDINATE SYSTEM

8 To make it easy to talk about where on the coordinate plane a point is, we divide the coordinate plane into four sections called quadrants. Points in Quadrant 1 have positive x and positive y coordinates. Points in Quadrant 2 have negative x but positive y coordinates. Points in Quadrant 3 have negative x and negative y coordinates. Points in Quadrant 4 have positive x but negative y coordinates.

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10 Write the coordinates of each point. A: (2, 3) B: (5, -3) C: (-1, -5)

11 WRITE THE COORDINATES FOR EACH POINT A: (6, 5) B: (4, 6) C: (2, 1) D: (-4, 3) E: (-5, 0) F: (-3, -2) G: (0, -4) H: (4, -4)

12 Every straight line can be represented by an equation: y = mx + b. The coordinates of every point on the line will solve the equation if you substitute them in the equation for x and y. EVERY POINT THAT FITS ON A LINE IS CALLED COLLINEAR. y = 2x = 2(1) + 1== YES 3 = 2(1) + 1== YES 5 = 2(2) + 1== YES THESE POINTS ARE COLLINEAR.

13 All segments shown are parallel to either the x- or y-axis. Determine the ordered pair that represents each point. J: (, )– 612 G: (, ) B: (, ) N: (, ) F: (, ) E: (, ) – – 2

14 POINTS G(1, – 1) AND H(3, 3) LIE ON THE LINE y = 2x – 3. Determine whether the following points are collinear to G and H. I (0, – 3) y = 2x – 3 – 3 = 2(0) – 3 YES J (2, 1) 1 = 2(2) – 3 YES K (– 3, –8) –8 = 2(–3) – 3 NO L ( 5, 7) 7 = 2(5) – 3 YES M ( 10, 16) 16 = 2(10) – 3 NO


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