Define abscissa?

Hint: Here, we will understand the meaning of the two terms used in the 2D coordinate geometry namely the abscissa and the ordinate. Further, we will see which of the following coordinates x and y coordinate is called the abscissa and which one is the ordinate. At last we will see the sign convention of the coordinates in the four quadrants.

Complete step-by-step solution:
Here we have been provided with the term abscissa and we are asked to explain it. Let us understand the two different terms used in the 2D coordinate geometry namely the abscissa and the ordinate.
Now, in 2D coordinate geometry we use the word abscissa for the x coordinate of a point. The term ordinate is used for the y coordinate of a point. For example: - if we have a point P (a, b) then here ‘a’ is called the abscissa and ‘b’ is called the ordinate. Let us see the graph of the point P (a, b) on the x- y plane.

In the above graph ‘a’ is the distance of the point from the x axis and ‘b’ is the distance of the point from the y axis. So we can also define the abscissa as the distance of a point from the y axis and similarly the ordinate is distance of the point from the x axis. There are four quadrants in the 2D Cartesian plane. In the first quadrant both x and y are positive, in the second x is negative and y is positive, in the third both are negative and in the fourth x is positive and y is negative.

Note: Note that in 3D coordinates we have three coordinates to define the position of a point given as P (a, b, c). Here ‘c’ is the z – coordinate also called as the applicate. Remember that the words abscissa and ordinate are sometimes used to refer to the coordinate axes rather than the coordinate values. Remember the sign of the x and y coordinates in all the four quadrants.