Consider the three points graphed. what is the value of y in the fourth point that will complete the quadrilateral as a rhombus?

COORDINATE GEOMETRY (A) Main Concepts and Results
Cartesian system Coordinate axes Origin
Quadrants
Abscissa
Ordinate
Coordinates of a point Ordered pair
Plotting of points in the cartesian plane:
• In the Cartesian plane, the horizontal line is called the x-axis and the vertical line
is called the y-axis,
• The coordinate axes divide the plane into four parts called quadrants,
• The point of intersection of the axes is called the origin,
• Abscissa or the x-coordinate of a point is its distance from the y-axis and the ordinate or the y-coordinate is its distance from the x-axis,
• (x, y) are called the coordinates of the point whose abscissa is x and the ordinate is y,
• Coordinates of a point on the x-axis are of the form (x, 0) and that of the point on the y-axis is of the form (0, y),
CHAPTER 3
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COORDINATE GEOMETRY 25
• The coordinates of the origin are (0, 0),
• Signs of the coordinates of a point in the first quadrant are (+, +), in the second quadrant (–, +), in the third quadrant (–, –) and in the fourth quadrant (+, –).
(B) Multiple Choice Questions
Write the correct answer :
Sample Question 1: The points (other than origin) for which abscissa is equal to the ordinate will lie in
(A) I quadrant only (B) I and II quadrants
(C) I and III quadrants (D) II and IV quadrants Solution : Answer (C)
EXERCISE 3.1
Write the correct answer in each of the following : 1. Point (–3, 5) lies in the
(A) first quadrant (B) second quadrant