Finished exercise 11.

ch1/exercises/ex11.c

@@ -1,9 +1,27 @@
-/* I'm currently working on exercise 12, since it looks way harder. */
+// Way to tell us about sqrt and pow.
+// You'll need to invoke the compiler like so: clang -g -lm ex11.c
+// I hope not all libraries need compiler flags...
 
 #include <stdio.h>
+#include <math.h>
+
+#define RECTANGLES	100
 
 int main(void) {
 
+	int i, radius = 2;
+	double height, area = 0, width = (float)radius / RECTANGLES;
+
+	double x = width / 2; // The first x value is the midpoint of the first rectangle.
+
+	for(i=0; i < RECTANGLES; i++) {
+		height = sqrt(pow(radius, 2) - pow(x, 2));
+		area += height * width;
+		x += width;
+	}
+
+	printf("The approximation of Π with %d rectangles is %.20f.\n", RECTANGLES, area);
+
 	return 0;
 
 }