Creating a tangent circle in graphing.

[webmasterpdx]

Lets say you want a line going through the origin at an angle of pi/2, then you'd enter the polar form, as 1<angle>(pi/2)
<angle> is shift-multiply
pi is shift-3

Then, you can just hit the angle key (shift-multiply) and it'll convert it into a complex number. You can then take the complex number as rectangular coordinates and 0,0 and draw a line between them....

...something like that :-)