Various exceptions may arise when an equation has two nearly equal roots. But I do not here introduce algebraical difficulties; and a student might give himself a hundred examples, taken at hazard, without much chance of lighting upon one which gives any difficulty.

This form might be also applied to the integer portions; but it is hardly needed in such instances as usually occur. See the article Involution and Evolution in the Supplement to the Penny Cyclopædia.

After the second step, the trial will rarely fail to give the true figure.

A four-sided figure, which has two sides parallel, and two sides not parallel.

The right angle is divided into 90 equal parts called degrees, each degree into 60 equal parts called minutes, and each minute into 60 equal parts called seconds. Thus, 2° 15′ 40″ means 2 degrees, 15 minutes, and 40 seconds.