## Trigonometry, Plane and Spherical: With the Construction and Application of Logarithms |

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4th rem ABC+ACB AC by Theor AC-BC AC+BC adjacent angle AF-co-f alfo alfo known alſo angle ACB bafe baſe becauſe bifecting cafe chord circle co-fecant co-fine AC co-tangent of half common logarithm confequently COROL COROLLARY diameter dius E. D. PROP equal to half excefs faid fame fecant fecond feries fhall fides AC fimilar triangles fines firft firſt fquare fupplement fuppofed garithms gles great-circles half the difference half the fum half the vertical Hence hyperbolic logarithm interfect itſelf laft laſt leffer leg BC likewife LUKE HANSARD moreover oppofite angle pendicular periphery perpendicular plane triangle ABC progreffion propofed proportion radius co-fine refpectively right-angled Spherical triangle right-line ſhall ſpherical triangles ABC tang tangent of half THEOREM theſe thofe thoſe Trigonometry verfed vertical angle whence whofe

### Popular passages

Page 3 - The circumference of every circle is supposed to be divided into 360 equal parts, called degrees; and each degree into 60 minutes, each minute into 60 seconds, and so on.

Page 30 - U to their difference, fo is the tangent of half the fum of thofe arches, to the tangent of half their difference; and, As the fum of the...

Page 4 - The fine, or right-fine, of an arch, is a right line drawn from one extremity of the arch, perpendicular to the diameter paffing through the other extremity. Thus BF is the fine of the arch AB or DB.

Page 33 - ... fo is the tangent of half the vertical angle, to the tangent of the angle which the perpendicular CD makes with the line CF, bifcding the vertical The Solution of the Cafes of righl-angled fpfierical Triangles, (Fig.

Page 33 - ABC, it will be, as the co -tangent of half the fum of the angles at the bafe, is to the tangent of half their difference, fo is the tangent of half the...

Page 43 - JJ/xJV; hence, The sum of the logarithms of any two numbers is equal to the logarithm of their product. Therefore, the addition of logarithms corresponds to the multiplication of their numbers.

Page 5 - BI, the sine of its complement HB. The tangent of an arc, is a right line touching the circle in one extremity of that arc, continued from thence to meet a line drawn from the centre through the other extremity ; which line is called the secant of the same arc : thus AG is the Ungent, and CG the secant of the arc AB.

Page 4 - A chord, or fubtenfe, is a right line drawn from one extremity of an arch to the other ; thus B £ is the chord or fubterife of the arch BAE, orBDE.

Page 13 - The straight line BE between the centre and the extremity of the tangent AE, is called the Secant of the arch AC, or of the angle ABC. COR. to def.