DOCS-934 review edits

Author: Bob Grabar

source/reference/operator/centerSphere.txt

@@ -18,18 +18,16 @@ $centerSphere
 
    - The center point
 
-   - The radian. To calculate the radian, divide the radius of
-     the circle by the radius of the sphere.
-
-      db.collection.find( { loc: { $within: { $centerSphere: [ [0,0], 10 / 3959 ] } } } )
+   - The angular distance in radians (distance along the surface of the
+     earth).
 
    The following example returns all documents within a 10 mile radius
-   of longitude ``88 W`` and latitude ``30 N``. The document determines
-   the radian by dividing 10 miles by the approximate radius of the earth:
-   3960 miles.
+   of longitude ``88 W`` and latitude ``30 N``. The distance (10 miles)
+   is converted to radians by dividing by the approximate radius of the
+   earth (3959 miles).
 
    .. code-block:: javascript
 
-      db.collection.find( { loc: { $within: { $centerSphere: [ [ 88 , 30 ], 10 / 3960 ] } } } )
+      db.collection.find( { loc: { $within: { $centerSphere: { [88,30], 10 /* miles */ / 3959 /* miles */ } } } } )
 
    .. include:: /includes/note-geospatial-index-must-exist.rst

source/reference/operator/within.txt

@@ -35,7 +35,7 @@ $within
 
         db.collection.find( { location: { $within: { $center: [ center, radius } } } );
 
-   - Circles measured by spherical geometry. Use the
+   - Circular distance on a sphere. Use the
      :operator:`$centerSphere` operator. For the syntax, see :operator:`$centerSphere`.
 
    - Polygons. Use the :operator:`$polygon` operator. Specify polygons with an array of points. See the