And tangent

math/exp.c

@@ -9,8 +9,9 @@
   I was stuck on how to actually implement the Taylor series without it
   getting far too big for even a long double, and I'm not sure I ever would
   have thought to just break it out recursively like this. Instead of each
-  term being x^n/n!, this says that it's (x/n+1)*(nth term), with a base case
+  term being x^n/n!, where we have to figure out both x^n and n!, both of which
-  of x/1! = x. Pretty clever, really.
+  could be massive, we instead say that it's (x/n+1)*(nth term), with a base 
+  case (1st term) of x/1! = x. Pretty clever, really.
 
   Also, really glad I know how to at least read a basic FORTRAN program. This
   probably would have been a little more annoying if I didn't.

math/sin.c

@@ -0,0 +1,5 @@
+#include <math.h>
+
+double sin(double x) {
+  return cos(x - M_PI_2);
+}

math/tan.c

@@ -0,0 +1,5 @@
+#include <math.h>
+
+double tan(double x) {
+  return (cos(x - M_PI_2) / cos(x))
+}