Another attempt at rewording the sphere equation

Author: hollasch

books/RayTracingInOneWeekend.html

@@ -483,9 +483,10 @@
 <div class='together'>
 Let’s add a single object to our ray tracer. People often use spheres in ray tracers because
 calculating whether a ray hits a sphere is pretty straightforward. Recall that the equation for a
-sphere centered at the origin of radius $R$ is $x^2 + y^2 + z^2 = R^2$. Put another way, for
-$(x,y,z)$ _inside_ the sphere, $x^2 + y^2 + z^2 < R^2$, for points _outside_ the sphere, $x^2 + y^2
-+ z^2 > R^2$, and for points _on_ the sphere, $x^2 + y^2 + z^2 = R^2$.
+sphere centered at the origin of radius $R$ is $x^2 + y^2 + z^2 = R^2$. Put another way, if a given
+point $(x,y,z)$ is on the sphere, then $x^2 + y^2 + z^2 = R^2$. If the given point $(x,y,z)$ is
+_inside_ the sphere, then $x^2 + y^2 + z^2 < R^2$, and if a given point $(x,y,z)$ is _outside_ the
+sphere, then $x^2 + y^2 + z^2 > R^2$.
 
 It gets uglier if the sphere center is at $(\mathbf{c}_x, \mathbf{c}_y, \mathbf{c}_z)$: