from the values calculated, as below, from the original equation.
A further exercise in maxima and minima is afforded by the following example:
The equation to a circle of radius , having its centre at the point whose coordinates are , , as depicted in Fig. 29, is:
.
This may be transformed into
.
Fig. 29.
Now we know beforehand, by mere inspection of the figure, that when , will be either at its maximum value, , or else at its minimum value, . But let us not take advantage of this