In the worksheet below, variable x can be returned to type name after being assigned a value , but concatenated variable name A||1 cannot. Is there a way to return a concatenated variable to type name after it has been assigned a value, so it can be re-used as an unknown in solve commands?

Concatenate_Question.mw

CubicRoots.mw

In your answer, please include the calculation of the lamina's area and the location of its centre of mass.

Lamina.mw

I am interested in the AC circuits which control electric motor performance.

I have installed the Syrup package, written by Joseph Riel, from the Application Centre but it seems to draw and solve only DC powered circuits.

Does Syrup have AC circuit capability?

If not, is there any available package written in Maple which can draw and analyse AC circuits, preferably one in which the circuit can be constructed by clicking circuit elements in an palette and dragging them to a canvas?

Finally, if there is no such Maple package, can you point me to an equivalent, free package which is downloadable from the internet? 

The uploaded worksheet contains a contourplot whose display I can't understand. Can you explain it?

Countourplot.mw