## A Treatise of Plane and Spherical Trigonometry: In Theory and Practice ; Adapted to the Use of Students ; Extracted Mostly from Similar Works of Ludlam, Playfair, Vince, and Bonnycastle |

### From inside the book

Results 1-5 of 13

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**yards**, and the angle at the base A 55 ° 30 ′ , to find the rest . Answer . BC = 99-719**yards**, AB = 68.535 , angle C = 34 ° 30 ' . Case 2. Given the side AB 125 , and the angle A 51 ° 19 ′ , to find the rest . By Construction . Draw an ... Page 42

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**yards**farther off , on a level with the bot- tom , it was 31 ° . Required its height . ABC 46 ° - ADC 31 ° DAB 15o . = Sine DAB 15 ° : sine D 31 . :: DB 100 : AB . Log . 100 Log . sine 31 ° Log . sine 15 ° A - · 2.0000000 · 9.7118393 ... Page 43

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**yards**distant from each other , were 64 ° and 35o . Re- quired its height , and its distance from the two places of observation . Answer . Height 935.757**yards**, greater distance 1631-442 , less distance 1041.125 . 4. From the top of a ... Page 44

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**yards**, as in prob . 2 . R or sine C 90 ° : cos . B 58 ° :: AB : BC . Log . cos . 58 ° Log . AB ( found ) Log . BC 84.05**yards**9.7242097 2.0823677 1.8065774 6. Being desirous to know the height of an obelisk erected on the top of a ... Page 46

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**yards**in a straight line by the side of it , and at the ends of this distance I took the an- gles formed by it and a tree on the opposite bank , which were B D 53 ° and 79 ° 12 ' . Required the breadth of the river . Angle BAC = 180 ...### Common terms and phrases

90 degrees adjacent angle AHDL algebra analogy angle ABC angle ACB Answer arc or angle base centre chord circle comp complement cosecant cosine cotangent Euclid's Elements find the angles find the rest geometry Given the side greater than 90 half the sum half their difference height Hence hypothenuse AC included angle less than 90 logarithmic sines mathematics measured mechanical philosophy negative opposite angle perp perpendicular plane triangle plane trigonometry PROP propositions quadrant AH quantity right-angled spherical triangle right-angled triangle Scholium secant side AB side AC sides and angles sine a sine sine and cosine sine² sines and tangents solution spherical angle spherical triangle ABC spherical trigonometry supplement tables tangent of half theorems third side three angles three sides triangle are given trigono versed sine yards

### Popular passages

Page 12 - In every plane triangle, the sum of two sides is to their difference as the tangent of half the sum of the angles opposite those sides is to the tangent of half their difference.

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

Page 23 - Then multiply the second and third terms together, and divide the product by the first term: the quotient will be the fourth term, or answer.

Page 13 - In any triangle, twice the rectangle contained by any two sides is to the difference between the sum of the squares of those sides, and the square of the base, as the radius to the cosine of the angle included by the two sides. Let ABC be any triangle, 2AB.BC is to the difference between AB2+BC2 and AC2 as radius to cos.

Page 87 - The cosine of half the sum of two sides of a spherical triangle is to the cosine of half their difference as the cotangent of half the included angle is to the tangent of half the sum of the other two angles. The sine of half the sum of two sides of a spherical...

Page 74 - The sum of any two sides is greater than the third side, and their difference is less than the third side.