Remove extraneous sentence on ray expression

Resolves #348

Author: hollasch

books/RayTracingInOneWeekend.html

@@ -351,16 +351,19 @@
 Rays, a Simple Camera, and Background
 ====================================================================================================
 
+<div class='together'>
 The one thing that all ray tracers have is a ray class, and a computation of what color is seen
 along a ray. Let’s think of a ray as a function $\mathbf{p}(t) = \mathbf{a} + t \vec{\mathbf{b}}$.
 Here $\mathbf{p}$ is a 3D position along a line in 3D. $\mathbf{a}$ is the ray origin and
 $\vec{\mathbf{b}}$ is the ray direction. The ray parameter $t$ is a real number (`double` in the
 code). Plug in a different $t$ and $p(t)$ moves the point along the ray. Add in negative $t$ and you
 can go anywhere on the 3D line. For positive $t$, you get only the parts in front of $\mathbf{a}$,
-and this is what is often called a half-line or ray. The example $\mathbf{c} = p(2)$ is shown here:
+and this is what is often called a half-line or ray.
 
   ![Figure [lerp]: Linear interpolation](../images/fig.lerp.jpg)
 
+</div>
+
 <div class='together'>
 The function $p(t)$ in more verbose code form I call `ray::at(t)`: