**PURPOSE: **To aid in perception of the components of a three-dimensional vector.

**DESCRIPTION: **An arbitrary vector in three-dimensional space is shown along with projections along the three orthogonal axes. Observe how the angles *alpha, beta, gamma* are defined.

**SUGGESTIONS: **Emphasize that the angle between the vector and any axis is not the same as the angle between the axis and the projection of the vector onto a plane defined by two axes.

**REFERENCES: ** (PIRA 1A40.10)

**EQUIPMENT: **Direction cosines model, as photographed.

**SETUP TIME: **None.