--- /dev/null
+.. _add_node_on_segment_page:
+
+*****************
+Cutting triangles
+*****************
+
+This operation cuts triangles into two by adding a node on an edge bounding these triangles.
+
+ .. image:: ../images/add_node_on_segment.png
+ :align: center
+
+*To cut triangles:*
+
+.. |img| image:: ../images/mesh_split_diag_interactive.png
+
+#. Select a mesh and display it in the 3D Viewer.
+#. In the **Modification** menu select the **Add node on segment** item or click *"Add node on segment"* button |img| in the toolbar.
+
+ The following dialog box will appear:
+
+ .. image:: ../images/add_node_on_segment-dlg.png
+ :align: center
+
+
+#. Enter IDs of nodes forming the edge in the **Edge** field (the node IDs must be separated by a dash) or select the edge in the 3D viewer.
+
+#. Enter location of a new node on the edge which is defined as a real number in the range between 0.0 and 1.0. You can define it
+
+ * by clicking with your mouse on the edge in the Viewer,
+ * by typing a number in a field,
+ * by setting a number using arrows of a spin box.
+
+#. Activate **Preview** to see a result of the operation.
+
+#. Click the **Apply** or **Apply and Close** button to confirm the operation.
+
+**See Also** a sample TUI Script of a :ref:`tui_cutting_triangles` operation.
