Geometrical trigonometry, or, The explanation of such geometrical problems as are most useful & necessary, either for the construction of the canons of triangles, or for the solution of them together with the proportions themselves suteable unto every case both in plain and spherical triangles ... / by J. Newton ...
About this Item
Title
Geometrical trigonometry, or, The explanation of such geometrical problems as are most useful & necessary, either for the construction of the canons of triangles, or for the solution of them together with the proportions themselves suteable unto every case both in plain and spherical triangles ... / by J. Newton ...
Author
Newton, John, 1622-1678.
Publication
London :: Printed for George Hurlock ... and Thomas Pierrepont ...,
1659.
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Subject terms
Trigonometry -- Early works to 1800.
Link to this Item
http://name.umdl.umich.edu/A52262.0001.001
Cite this Item
"Geometrical trigonometry, or, The explanation of such geometrical problems as are most useful & necessary, either for the construction of the canons of triangles, or for the solution of them together with the proportions themselves suteable unto every case both in plain and spherical triangles ... / by J. Newton ..." In the digital collection Early English Books Online. https://name.umdl.umich.edu/A52262.0001.001. University of Michigan Library Digital Collections. Accessed June 19, 2025.
Pages
Illustration by Artificial numbers.
As the side CB 632 2.800717
Is to the sine of D 26.37 9.647545
So is the sides CD 865 2.937016
12.584561
To the sine of B 37.43 9.783844
2 Probl. Two sides with the angle
comprehended by them given, to find ei∣ther
of the other angles.
In the Oblique angled plain Tri∣angle
BDC.
The angle DBC is inquired.
descriptionPage 65
The given
Sides
DC
BC
The given
Angle DCB
Subtract the angle given, out of 180d.
the remainer is the sum of the other
angles, and
½ Z c••ur. DC and BC. ½ X crur ∷
t ½ Z ang. t ½ X ang. by the 3 Ax.
To the half sum of the other angles,
adde the half difference found, and
you will have the greater angle, sub∣duct
it & you will have the lesser, in our
example ½ Z ang. + ½ Xang. is = DBC
sought, because that is the greater ang.
3 Probl. The angles and a side gi∣ven,
to find either of the other sides.
In the Oblique angled plain triangle
CBD,
The side DB is inquired.
The given
Angles
DCB
CDB
The given
Side CB
s. CDB, CB ∷ s. DCB. DB. by the
second Axiome.
descriptionPage 66
4 Probl. Two sides with the angle
comprehended by them given, to find the
third side.
In the oblique angled plain triangle
DCB
The side CB is inquired.
The given
Sides
DB
CB
The given
Angle CBD
First, find the angle BCD by the
third Axiome.
Secondly, find the side CB by the se∣cond
Axiome.
5 Probl. The three sides given to find
an angle.
In the Oblique angled plain trian∣gle
CBD.
The angle CDB is inquired.
The three sides be∣ing
given.
DC
CB
DB
The resolution of this Problem
doth require two operations, first, for
the segment of the base GB.
descriptionPage 67
DB.Z crur. DC & CB ∷ X crur. GB.
••y the fourth axiome.
And DB − GB = DG, and ½ DG
=DA or AG.
And DC. Rad ∷ AD. s ACD, by
the second axiome whose complement
••s ADC.
And AG + GB = AB, therefore
ang. ABC may be also found in like
manner.
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