18 New Principles of Gardening. 
fore calleda Triangle. When a Triangle hath all its Sides equal; 
tis called an Eguslateral Triangle, as eab. ‘That Triangle as: 
hath two Sides equal, and the third unequal, is called an L/o- 
celes Triangle, and that Triangle whofe three Sides are un- 
equal, as 401, is called a Scalenum Triangle. 
Note, That what is here delivered in relation to the Names 
of Triangles, is only with refpe@ to their Sides; therefore, 
when Triangles are mentioned with regard ro their Angles, 
they are diftinguifhed as following, viz. 4 Right-angled Trian- 
gle, is that which has one Right Angle and two Acute Angles, 
as gh/ right-angled at g, and acute-angled at 4and/. All 
Angles are meafured by an Arch of a Circle, whofe Center is 
the Angular Point; and the Number of Degrees contained in fuch 
an Arch, is the Quantity of the Angle. 
If the Quantity of the Angle is ninety Degrees, as the An- 
gle 1, 2, 5, “tis calleda Right Angle; and when lefs than ninety 
Degrees, ’tis called an Acute Angle, as the Angle 3,2, 4; but 
when the Angle is greater than a Right Angle, containing more 
than ninety Degrees, fuch an Angle is called an Obtu/e Angle. 
Figs. An Amblygonium Triangle is that as hath one Obtufe Angle, 
XXXVI and two Acute Angles, as boi. An Oxigonium Triangle is 
that as hath all its Angles acute, as ahd. Inevery plain Tri- 
angle, the Sum of the three Angles are always equal to 180 
‘Degrees. In every Triangle, any two of the Lines being ta- 
ken for two Sides, the other remaining (be which it wiil) is 
called the Ba/é ; therefore any Side of a Triangle may be made 
the Ba/e. aia 
Inall right-angled Plain Triangles, that Side as is oppofite to 
the Right Angle, is called the Aypothenufe, and the other two 
Sides its Legs; and fometimes one of the Legs is called the Bafe, 
and the other (Cathetus, a Greek Word for) Perpendicular. 
Practice. Make edé equal to fg, and on e.and4, with 
the Interval fg, defcribe the Arches 1, 1, and 2, 2, croffing in a; 
join 24 and ae, the Triangle required; for as 26, be, and ea, 
are ie — Circles, thereforethe Triangle is Equila- 
teral. si. 
PRO Bs 
