Question

If a point is located above the xy-plane, then which coordinate(s) must be positive?

Option 1: the y-coordinate
Option 2: the z-coordinate
Option 3: the x- and y-coordinates
Option 4: the y- and z-coordinates

Answer 1

When a point is above the xy-plane, the z-coordinate must be positive, as it indicates vertical position above the plane.

Step-by-step explanation:

If a point is located above the xy-plane, the coordinate that must be positive is the z-coordinate. This is because the z-coordinate determines the position of a point vertically above or below the xy-plane. According to the right-hand rule for a Cartesian coordinate system, the thumb points along the positive x-axis, the index finger points along the positive y-axis, and the middle finger points along the positive z-axis. So, when a point is above the plane, the z-value must be positive regardless of the x- and y-coordinates. Therefore, the correct answer to which coordinate must be positive is Option 2: the z-coordinate.