The figure at the left shows a generic spherical coordinate system, with the radial coordinate denoted by q, the zenith (the angle from the North Pole; the colatitude) denoted by a, and the azimuth (the angle in the equatorial plane; the longitude) by b.
What symbols do you use for (q,a,b)?
If the Greek letter theta doesn't look right in your browser, look at
these instructions.
If all else fails, try the
symbol-free version.