Gasket
In Parametric Modeling with Autodesk Inventor for 2013, the textbook for Engineering Graphics the gasket shown below is used to demonstrate the OFFSET Cut command. In demonstrating the process for reproducing the offset, Mr Shih missed a crucial step. Immediately, after beginning the second sketch the Project Geometry command must be selected to implement the offset. Unfortunately couldn't make a video to upload but these are the steps:
1 On the ribbon tab select Create 2D sketch to create a new or 2nd sketch
2 Go 1/3 of the way across on the ribbon tab and select the Project Geometry
3 Select the edges or curves to be offset
4 When the offset is complete, right click and select Continue
5 Trim any excess/extend any missing lines
6 Right click, select Finish Sketch
7 Extrude and cut to get the completed 3d model illustrated below