First Part of an Elementary Treatise on Spherical Trigonometry1836 - Spherical trigonometry - 71 pages |
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Page 11
... differ less from 90 ° than a does , as is evident from the following Lemma . ( 506 ) 10. Lemma . Of angles less than 180 ° , the one which differs the least from 90 ° has the largest sine , tangent , and secant ; and the smallest cosine ...
... differ less from 90 ° than a does , as is evident from the following Lemma . ( 506 ) 10. Lemma . Of angles less than 180 ° , the one which differs the least from 90 ° has the largest sine , tangent , and secant ; and the smallest cosine ...
Page 12
... 90 ° , the first member of ( 470 ) cos . A cos . a sin . B is positive , and therefore the factor cos . a of the sec ... differs less from ( 519 ) 90 ° than its opposite leg , the case of either side , equal to 90 ° , being ...
... 90 ° , the first member of ( 470 ) cos . A cos . a sin . B is positive , and therefore the factor cos . a of the sec ... differs less from ( 519 ) 90 ° than its opposite leg , the case of either side , equal to 90 ° , being ...
Page 13
... differs less from 90 ° than does a . ( 521 ) 13. Corollary . When , in a spherical right triangle , either side is equal to 90 ° , one of the other two sides ( 522 ) is also equal to 90 ° ; and each side is equal to its op- posite angle ...
... differs less from 90 ° than does a . ( 521 ) 13. Corollary . When , in a spherical right triangle , either side is equal to 90 ° , one of the other two sides ( 522 ) is also equal to 90 ° ; and each side is equal to its op- posite angle ...
Page 15
Benjamin Peirce. Demonstration . First Case . When each of the legs differs from 90 ° , the equation ( 470 ) , cos . A = cos . a sin . B , ( 541 ) gives , by ( 520 ) , cos . Asin . B ; ( 542 ) or , by ( 5 ) , ( 543 ) sin . ( 90 ° - A ) ...
Benjamin Peirce. Demonstration . First Case . When each of the legs differs from 90 ° , the equation ( 470 ) , cos . A = cos . a sin . B , ( 541 ) gives , by ( 520 ) , cos . Asin . B ; ( 542 ) or , by ( 5 ) , ( 543 ) sin . ( 90 ° - A ) ...
Page 18
... differs from 90 ° while that of A is equal to 90 ° . h EXAMPLES . 1. Given in the spherical right triangle ( fig . 2. ) , 145 ° and A 23 ° 28 ' ; to solve the triangle . Solution . by ( 561 ) , By ( 558 18 SPHERICAL TRIGONOMETRY . [ си ...
... differs from 90 ° while that of A is equal to 90 ° . h EXAMPLES . 1. Given in the spherical right triangle ( fig . 2. ) , 145 ° and A 23 ° 28 ' ; to solve the triangle . Solution . by ( 561 ) , By ( 558 18 SPHERICAL TRIGONOMETRY . [ си ...
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Common terms and phrases
A'BC AC the perpendicular adjacent angles angle are known angles are given angles respectively equal AP and PC ar.co B'OC Corollary cosec cosine of half cotan Demonstration differs from 90 equal to 90 fall on AC given angle given sides given value greater than 90 h tang half the sum Hence hypothenuse included angle legs are known Lemma less than 90 Let ABC fig let fall logarithm lunary surface means of 496 middle Napier's Rules negative obtuse opposite angle opposite side perpendicular BP perpendicular to OA planes BOC Problem quotient right angle right triangle fig right triangle PBC Scholium second member Secondly side BC sides and angles sides equal Solution of Spherical solve a spherical solve the triangle Spherical Oblique Triangles spherical right triangle spherical triangle ABC SPHERICAL TRIGONOMETRY substituted surface ABC tang.b tangent of half Thirdly trian triangle ABC figs
Popular passages
Page 1 - A spherical triangle is a portion of the surface of a sphere, bounded by three arcs of great circles.
Page 69 - The areas of two triangles which have an angle of the one equal to an angle of the other are to each other as the products of the sides including the equal angles. D c A' D' Hyp. In triangles ABC and A'B'C', ZA = ZA'. To prove AABC = ABxAC. A A'B'C' A'B'xA'C' Proof. Draw the altitudes BD and B'D'.
Page 69 - THEOREM. The surface of a spherical triangle is measured by the excess of the sum of its three angles above two right angles, multiplied by the tri-rectangular triangle.
Page 8 - I. The sine of the middle part is equal to the product of the tangents of the adjacent parts.
Page 8 - II. The sine of the middle part is equal to the product of the cosines of the opposite parts.
Page 30 - Any angle is greater than the difference between 180° and the sum of the other two angles.
Page 63 - 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 62 - The sine of half the sum of two sides of a spherical triangle is to the sine of half their difference as the cotangent of half the included angle is to the tangent of half the difference of the other two angles.
Page 71 - ... and the sum of the angles in all the triangles is evidently the same as that of all the angles of the polygon ; hence, the surface of the polygon is equal to the sum of all its angles, diminished by twice as many right angles as it has sides less two, into the tri-rectangular triangle.