You can find any tool by the Menu Structure HERE: https://turbocaddoc.atlassian.net/wiki/display/TC20UG/Menu+Structure
You can find the menu location of any tool by name HERE: https://turbocaddoc.atlassian.net/wiki/display/TC20UG/Tools+Mapped+to+Menus
Arc
Most of the Arc tools are identical to Circle/Ellipse tools. After the initial circle is created, the arc is cut from it by defining the start and end angles.
You can display the Arc toolbar by right-clicking in any toolbar area and selecting Arc.
Start and end angles can be changed with the Edit Tool (node editing). See Editing Circles, Ellipses, and Arcs.