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A Table to Reduce Sexagenary Mi-
nutes, to Centesimal Parts; and
the contrary.
Cent.

Sexag.

Cent.

Sexag.
Minut. Parts. Minut. Parts.

31.51.67
32 53.33

33.55.
34.56.67
3558.32
36.60.

6

.10.

71.11.67
8.13.33

37.6167

38.63.33

6.15.

39.65.

10

.16.67

40.6667

II

.18.33

12 .20.

13.21.67

14.23.33

15.25.

16.26.67 17.28.33 18.30. 19.31.67

20

21

.25.23

•35.
22.33.67
23 .38.33

24.40.
25.41.67

:

-

41.68.33
42.70.
43.71.67

44 73.33

45.75.

46.76.67
47.78.33
48.80.
49 .81.67
50.83.32

51.85.

of this Book which treateth of Trigonometry, where the Angles of Right-lined, and the Sides and Angles of Spherical Triangles are meafured by Arches of Circles; and those Arches are usually numbred (or accounted) by Degrees, Minutes, Seconds, &c. Of which one Degree contains 60 Minutes, One

Minute 60 Seconds, &c. which is called the Sexary Division of the Degree. Or otherwise, the Degree is supposed to be divided into 100 or 1000 Parts, which is called the Centefimal, Millefimal, &c. Division, (and is the better of the Two in many Respects.)

Now, whereas in the following Trigonometrical Calculations of this Book,

52.86.67 and also in the other

54.90.

53.88.33

559167

Parts (which concern the Doctrine of Triangles applied to Practice in feveral Parts of the Mathematicks) I have, some

58.96.67

times, used the Sexagena

59.98.33

ry, and fometimes the

60

Čentesimal, Way of Di

viding the Degree: (Not that I intended to make a Difference, (or rather a Confufion, by intermixing them) but because these several Tradates were not written at the same time, nor, at firft, intended to be joined together, as here they are: But fince it so is, I have here (in the beginning) inferted a short Table, by which Sexagenary Minutes are Reduced to Centesimal or Millefimal Parts: And also, Centesimal Parts to Minutes and Seconds: So that when the Reader meets with either of them, in any Part of these Tractates, he need not be at any Stand) (or Demurr about it) but readily know, to which Account it belongs, for the Manner of writing them will discover it: So 23 Deg. 30 Min. is written as here; but the same written Centesimally, thus, 23.5 Deg. Also 56 Deg. 43 Min. is written Sexagenarily, as here, but the fame Centesimally, thus, 56.71 Deg. or Millefimally, thus, 56.716 Deg. And fo of all others, as in the Table.

Of the Solution, Calculation, or Mensuration, of Rightangled Plain Triangles.

I comprehend the Right the stand side

N Right-angled Plain Triangles, I call those Sides, which Fig. XII.

tending the Right Angle, I call the Hypotenuse; and the Triangle which I shall make use of in the Resolving the Seven CASES following shall be that Diagram noted with M, in Fig. XII. Whose Diagram

Sides and Angles are,

Side

{

Angles

A B 235.00

BC 274 93

Μ.

CASE I. The Legs A B and A C given, to find the Angle C. Fig. XII.

PROPORTION.

As Log. AC: Radius :: Log. A B: 1C. [By Axi. I.

G2

OPE

Cafe I.

Fig. XII. CASE II. The Angles C and B, and the Leg. A B given; To

Cafe II. find the Leg. A C.

PROPORTION.

As Rad. : Leg. AB::tB: Log. AC. [By Axi. I.

Cafe III. find the Angle C.

10.

2.3710678

9.7883979

12.1544657

Fig. XII. CASE III. The Hypotenuse BC, and the Leg. A B given, To

PROPORTION.

As Leg. BC: Rad. :: Leg. A B.SC. [By Axi. II.

Fig. XII. CASE IV. The Hypotenuse B C, and the Angles B and C, gi

Cafe IV. ven; To find the Leg. A B.

PROPORTION.

As Radius: Hyp. BC :: SC, : Leg. A B. [By Axi. II.

OPE