diff --git a/src/stereographic_extrude.scad b/src/stereographic_extrude.scad
index 9e139977..406cf7fe 100644
--- a/src/stereographic_extrude.scad
+++ b/src/stereographic_extrude.scad
@@ -12,11 +12,10 @@ module stereographic_extrude(shadow_side_leng, convexity = 1) {
     half_side_length = shadow_side_leng / 2;
     outer_sphere_r = half_side_length / 3;
 
-    denominator = sqrt(4 * outer_sphere_r ^ 2 + 2 * half_side_length ^ 2);
-    cosa = 2 * outer_sphere_r / denominator;
-    sina = sqrt(2) * half_side_length / denominator;
+    x = 2 * outer_sphere_r;
+    y = sqrt(2) * half_side_length;
 
-    inner_sphere_r = outer_sphere_r * sina;
+    inner_sphere_r = outer_sphere_r * y / norm([x, y]);
     
     intersection() { 
         translate([0, 0, outer_sphere_r]) 
@@ -24,9 +23,9 @@ module stereographic_extrude(shadow_side_leng, convexity = 1) {
             sphere(outer_sphere_r);
             sphere((outer_sphere_r + inner_sphere_r) / 2);
             
-            translate([0, 0, outer_sphere_r / 2]) 
+            #translate([0, 0, outer_sphere_r / 2]) 
             linear_extrude(outer_sphere_r) 
-                circle(inner_sphere_r * cosa);
+                circle(inner_sphere_r / 2);
         }
      
         linear_extrude(outer_sphere_r * 2, scale = 0.01, convexity = convexity)