Question

Imagine the YZ plane in front of you. The z-axis is towards your right and the y-axis points vertically up. Then the x-axis is .

• A. out of the plane
• B. into the plane
• C. towards the left
• D. vertically downwards

Answer 1

The correct option is A out of the plane

In a righ handed coordinate system, the direction of the axes is determined by the right hand rule. If you curl the fingers of your right hand around the z-axis in the direction of a 90◦ counterclockwise rotation from the positive x-axis to the positive y-axis, then your thumb points in the positive direction of the z-axis. In this case the z-axis is towards the viewer’s right. So the x-axis should be inward for it to be consistent with the rule.