HELP PLZ: How do I turn on Symmetric Icon Relation in Solidworks 2011?

Hi, I am learning SolidWorks from the book "Introduction to solid modeling using Solidworks 2011"

In one of the step they ask for drawing a "Corner Rectangle", select the 2 sides and then use "Make Symmetric" icon which can be found in the context toolbar.

But I dont see any thing like that, all I see was "make vertical, horizontal, parallel,..."

And I am using the Student Development Kit.

Please help me find this relation icon.

Thanks.

SolidworksGeneral