I have a question about plotting two functions that have a common argument, e.g. time, in a single figure, such that the values of one function are used for the x-axis and the those of the second function for the ordinary y-axis.
How can we for example specify two functions $x=f_1(t)$ & $y=f_2(t)$ such that when plotting these two functions in a single figure, a circle is created by varying the variable t?
Any help would be really appreciated.
This is called parametric representation.
For the circle you want $$ f(t) = (\cos t, \sin t). $$
This traces the full circle as $t$ varies from $0$ to $2\pi$.