1 files changed, 2 insertions, 5 deletions
diff --git a/examples/widgets/graphicsview/elasticnodes/edge.cpp b/examples/widgets/graphicsview/elasticnodes/edge.cpp
index e794e803cf..d9e4c62e34 100644
--- a/examples/widgets/graphicsview/elasticnodes/edge.cpp
+++ b/examples/widgets/graphicsview/elasticnodes/edge.cpp
@@ -51,12 +51,11 @@
 #include "edge.h"
 #include "node.h"
 
-#include <math.h>
+#include <cmath>
 
 #include <QPainter>
 
 static const double Pi = 3.14159265358979323846264338327950288419717;
-static double TwoPi = 2.0 * Pi;
 
 //! [0]
 Edge::Edge(Node *sourceNode, Node *destNode)
@@ -139,9 +138,7 @@ void Edge::paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *)
 
 //! [6]
     // Draw the arrows
-    double angle = ::acos(line.dx() / line.length());
-    if (line.dy() >= 0)
-        angle = TwoPi - angle;
+    double angle = std::atan2(-line.dy(), line.dx());
 
     QPointF sourceArrowP1 = sourcePoint + QPointF(sin(angle + Pi / 3) * arrowSize,
                                                   cos(angle + Pi / 3) * arrowSize);