fix a typo

Author: f-frhs

src/Spatial/Euclidean/Circle2D.cs

@@ -171,8 +171,8 @@ private double[] findParameterTs(Line2D line)
             var b = 2 * (s.DotProduct(d) - d.DotProduct(cc));
             var c = (s - cc).DotProduct(s - cc) - r * r;
 
-            var soluions = FindRoots.Polynomial(new[] { c, b, a });
-            var ts = soluions
+            var solutions = FindRoots.Polynomial(new[] { c, b, a });
+            var ts = solutions
                 .Where(z => z.IsReal())
                 .Select(z => z.Real)
                 .ToArray();