Spherical coordinate entry in 3D is similar to polar coordinate entry in 2D. You locate a point by specifying its distance from the origin of the current UCS, its angle from the X axis (in the XY plane), and its angle from the XY plane, each angle preceded by an open angle bracket (<):
X[angle from X axis][angle from XY plane]
In the following illustration, the coordinate 8<60<30 indicates a point 8 units from the origin of the current UCS in the XY plane, 60 degrees from the X axis in the XY plane, and 30 degrees up the Z axis from the XY plane. The coordinate 5<45<15 indicates a point 5 units from the origin, 45 degrees from the X axis in the XY plane, and 15 degrees up from the XY plane.
When you need to define a point based on a previous point, you can enter relative spherical coordinates by preceding them with the @ symbol.