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.
Rights/Permissions

To the extent possible under law, the Text Creation Partnership has waived all copyright and related or neighboring rights to this keyboarded and encoded edition of the work described above, according to the terms of the CC0 1.0 Public Domain Dedication (http://creativecommons.org/publicdomain/zero/1.0/). This waiver does not extend to any page images or other supplementary files associated with this work, which may be protected by copyright or other license restrictions. Please go to http://www.textcreationpartnership.org/ for more information.

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.

Page 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 cur. 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.

Page 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.

Page 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.

Do you have questions about this content? Need to report a problem? Please contact us.