Update src/2_coordinates.md

src/2_coordinates.md

@@ -351,35 +351,33 @@ We have discussed four different coordinate systems:
     $${\bf r} = (x_1, \ldots, x_n).$$ This systems can be
     used for any dimension $n$. It is particularly convenient for: infinite spaces, systems
     with rectangular symmetry.
-
     Distance between two points ${\bf r} = (x_1, \ldots, x_n)$ and
     ${\bf r}' = (x'_1, \ldots, x'_n)$:
     $$\Delta s^2 = (x'_1 - x_1)^2 + (x'_2 - x_2)^2 + \ldots + (x'_n - x_n)^2.$$
 
-2.  *Polar coordinates*: $${\bf r} = (r, \phi).$$ This system can be used in two
+2.  !!! tip "Polar coordinates" 
+    $${\bf r} = (r, \phi).$$ This system can be used in two
     dimensions. It is particularly suitable for systems with circular symmetry or functions
     given in terms of these coordinates.
-
     Infinitesimal distance: $$ds^2 = dr^2 + r^2 d\phi^2.$$
     Infinitesimal area: $$dA = r dr d\varphi.$$
 
-3.  *Cylindrical coordinates*: $${\bf r} = (r, \phi, z).$$ Can be
-    used in three dimensions. Suitable for systems with axial symmetry
+3.  !!! tip "Cylindrical coordinates" 
+    $${\bf r} = (r, \phi, z).$$ This system can be
+    used in three dimensions. It is particularly suitable for systems with axial symmetry
     or functions given in terms of these coordinates.
-
     Infinitesimal distance: $$ds^2 = dr^2 + r^2 d\phi^2 + dz^2.$$
     Infinitesimal volume:: $$dV = r dr d\varphi dz.$$
 
-4.  *Spherical coordinates*: $${\bf r} = (r, \theta, \phi).$$ Can be
-    used in three dimensions. Suitable for systems with spherical
+4.  !!! tip "Spherical coordinates" 
+    $${\bf r} = (r, \theta, \phi).$$ This sysytem can be
+    used in three dimensions. It is particularly suitable for systems with spherical
     symmetry or functions given in terms of these coordinates.
-
     Infinitesimal distance:
     $$ds^2 =r^2 (\sin^2 \theta d\phi^2 + d\theta^2) +  dr^2 .$$
     Infinitesimal volume:
     $$dV = r^2 \sin(\theta) dr d\theta d\varphi.$$ 
 
-
 ## 2.5. Problems
 
 1.  [:grinning:] *Warm-up*