Minor improvements of some LaTex equations

Author: MartinOtter

docs/src/internal/ContactForceLaw.md

@@ -187,22 +187,22 @@ The default $r_{contact}$ values for each shape are:
 |[FileMesh](@ref) | shortestEdge/2                  | false  |
 
 For flat shapes, [Box](@ref) and [Beam](@ref), $r_{contact}$ is only used,
-if two flat shapes are in contact with each other ($r_i$ is the contact sphere radius $r_{contact}$ of shape $i$):).
+if two flat shapes are in contact with each other ($r_i$ is the contact sphere radius $r_{contact}$ of shape $i$):
 
-| isFlat | isFlat           | $\mu_{r,geo}$               |
-|:-------|:-----------------|:----------------------------|
-|false   | false            | $\frac{r_1 r_2}{r_1 + r_2}$ |
-|false   | true             | $r_1$                       |
-|true    | false            | $r_2$                       |
-|true    | true             | $\frac{r_1 r_2}{r_1 + r_2}$ |
+| isFlat | isFlat           | $\mu_{r,geo}$                |
+|:-------|:-----------------|:-----------------------------|
+|false   | false            | $\dfrac{r_1 r_2}{r_1 + r_2}$ |
+|false   | true             | $r_1$                        |
+|true    | false            | $r_2$                        |
+|true    | true             | $\dfrac{r_1 r_2}{r_1 + r_2}$ |
 
 The factors $n_{geo}, c_{geo}$ in the definition of $f_n$ are computed with the
 equations for Hertz pressure:
 
 ```math
 \begin{align}
-$n_{geo} &= 1.5$
-$c_{geo} &= \frac{4}{3} \sqrt(\mu_{r,geo})$
+n_{geo} &= 1.5 \\
+c_{geo} &= \dfrac{4}{3} \sqrt{\mu_{r,geo}}
 \end{align}
 ```