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The Coordinate Plane. Vocabulary. Coordinate plane- it is formed by two number lines that intersect at right angels. The point of intersection is the 0 on each number line Axes- the two number lines X-axis- the horizontal axis Y-axis- the vertical axis
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Vocabulary • Coordinate plane- it is formed by two number lines that intersect at right angels. The point of intersection is the 0 on each number line • Axes- the two number lines • X-axis- the horizontal axis • Y-axis- the vertical axis • Origin- the point where the axes intersect • Quadrants- four areas that are formed by the two axes
What does this mean? Coordinate Plane
More Vocabulary • Ordered pair-a pair of numbers that gives the location of a point on a coordinate plane. The first number tells how far to the right (positive) or left (negative) the point is located from the origin. The second number tells how far up (positive) or down (negative) the point is located from the origin. • Coordinates- the numbers in an order pair • X-coordinate- first number in the ordered pair • Y-coordinate- second number in the ordered pair
Steps to finding coordinates of point D: • -Start at the Origin. Count horizontally along the x-axis until you are directly below point D. • We counted ____ units. • Did we move left or right? • Negative or positive? • The x-coordinate of D is____. • -Now count vertically until you reach point D. • -We counted _____ units. • Did we move up or down? • Negative or positive? • The y-coordinate of D is___. • The coordinates of D are (__,___). • D is in quadrant ____. Find the points: A, B, C
Discussion • If both coordinates of a point are negative, in which quadrant is the point located? • Describe the coordinates of all points in Quadrant I.
Graphing Points Draw a creative picture to represent locations in the town: Home: (-4, 2) Coffee Shop: (3,2) Church: (5, -2) School: (4, -5) Library: (-4, -5) Arcade: (-2, 0) Post Office (0,3)
Activity! Plot points to find a hidden picture!
Refresh • Plot these points in your coordinate plane: • A (-5, 4) • B (-9, -2) • C (7, 5) • D (-3, 8)
Reflecting points across the x-axis • A (-5, 4) • B (-9, -2) • C (7, 5) • D (-3, 8)
Reflecting points across the y-axis • A (-5, 4) • B (-9, -2) • C (7, 5) • D (-3, 8)
Discussion • What is the relationship between the coordinates of a point and the coordinates of its reflection across each axis? • A point in Quadrant II is reflected across the x-axis. The new point is located in Quadrant__. • A point in Quadrant____ is reflected across the y-axis. The new point is located in Quadrant II.