Plane trigonometry, by S.L. Loney.

2

TRIGONOMETRY.

- 3. On this account another system of measurement
called the Centesimal, or French, system has been
proposed. In this system the right angle is divided into
100 equal parts, called Grades; each grade is subdivided
into 100 Minutes, and each minute into 100 Seconds.
The symbols 1g, 1', and 1" are used to denote a Grade,
a Minute, and a Second respectively.
Thus 100 Seconds (100") make One Minute (1'),
100 Minutes (100'),,,, Grade, (1),
100 Grades (100g),,,, Right angle.
- 4. This system would be much more convenient to
use than the ordinary Sexagesimal System.
As a preliminary, however, to its practical adoption, a
large number of tables would have to be recalculated.
For this reason the system has in practice never been used.
- 5. To convert Sexagesimal into Centesirmal Measure,
and vice versa.
Since a right angle is equal to 90~ and also to 100g, we
have
90~= 100g.
lOg 90. 1= 9, and 1g-=
9 )10'
Hence, to change degrees into grades, add on oneninth; to change grades into degrees, subtract one-tenth.
Ex. S^s360= 36+ x36 =40s,
and 64g= 64 - x64 = (64- 6'4)~ =576~.
If the angle do not contain an integral number of
degrees, we may reduce it to a fraction of a degree and
then change to grades.