**In main**: type function. Interactive -> Calculation -> Line -> (Normal | Tan line)
**In graph**: define function. Analysis -> Sketch -> (Normal | Tan line). Type $x$ value to solve for a point. Return to show equation for line.
+
+## Stationary points
+
+Stationary where $m=0$.
+Find derivative, solve for ${dy \over dx} = 0$
+
+### Type of stationary points
+
+
+
+**Local maximum at point $A$**
+- $f^\prime (x) > 0$ left of $A$
+- $f^\prime (x) < 0$ right of $A$
+
+**Local minimum at point $B$**
+- $f^\prime (x) < 0$ left of $B$
+- $f^\prime (x) > 0$ right of $B$
+
+**Stationary** point of inflection at $C$
+