An Elementary Treatise on Plane and Spherical Trigonometry: With Their Applications to Navigation, Surveying, Heights and Distances, and Spherical Astronomy, and Particularly Adapted to Explaining the Construction of Bowditch's Navigator and the Nautical Almanac |
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Page 17
... terms only of those which are given at the outset ; but it is occasionally better , for practical reasons , in the working of a numerical example , to compute certain of the unknown parts first , and then use these in finding the others ...
... terms only of those which are given at the outset ; but it is occasionally better , for practical reasons , in the working of a numerical example , to compute certain of the unknown parts first , and then use these in finding the others ...
Page 22
... terms of the trigonometric functions of the two latter angles ; or , more briefly , To find the sine of the sum of two angles . N. Solution . Let the two angles be CAB and B'AC ( fig . 9 ) , repre- sented by the letters M and At any ...
... terms of the trigonometric functions of the two latter angles ; or , more briefly , To find the sine of the sum of two angles . N. Solution . Let the two angles be CAB and B'AC ( fig . 9 ) , repre- sented by the letters M and At any ...
Page 28
... term of both numerator and denominator of the second member by cos . M cos . N ; tang . ( M + N ) : = sin . M cos . N cos . M cos . N + cos . M sin . N cos . M cos . N cos . M cos . N sin . M sin . N cos . M cos . N cos . M cos . N sin ...
... term of both numerator and denominator of the second member by cos . M cos . N ; tang . ( M + N ) : = sin . M cos . N cos . M cos . N + cos . M sin . N cos . M cos . N cos . M cos . N sin . M sin . N cos . M cos . N cos . M cos . N sin ...
Page 29
... terms in the value of tang . ( M + N ) to obtain that of tang . ( M - N ) . This change , being made in ( 60 ) , produces tang . ( M - N ) tang . M - tang . N 1 + tang . M tang . N ( 61 ) Thirdly . As the cotangent is merely the ...
... terms in the value of tang . ( M + N ) to obtain that of tang . ( M - N ) . This change , being made in ( 60 ) , produces tang . ( M - N ) tang . M - tang . N 1 + tang . M tang . N ( 61 ) Thirdly . As the cotangent is merely the ...
Page 37
... terms of the fraction would increase its value ; and , therefore , the tangent of an acute angle in- creases with the increase of the angle . IV . The cosecant , secant , and cotangent of an angle are , by ( 6 ) , the respective ...
... terms of the fraction would increase its value ; and , therefore , the tangent of an acute angle in- creases with the increase of the angle . IV . The cosecant , secant , and cotangent of an angle are , by ( 6 ) , the respective ...
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Common terms and phrases
A₁ aberration acute adjacent Aldebaran ascension and declination azimuth celestial equator celestial sphere circle computed Corollary corr correct central altitude correction of Table corresponding cosec cosine cotan denote departure diff difference of latitude difference of longitude dist earth ecliptic equal to 90 formulas gives Greenwich Hence horizon horizontal parallax hour angle hypothenuse included angle interval mean meridian altitude method middle latitude miles moon moon's motion Napier's Rules Nautical Almanac Navigator obliquity observer at Boston obtuse opposite parallax perpendicular plane pole position prime vertical Problem Prop R₁ radius rhumb right ascension sailing Scholium secant second member semidiameter sideral sideral day solar Solution solve the triangle spherical right triangle spherical triangle star star's sun's tang tangent Theorem transit Trig true latitude vernal equinox vertical whence zenith
Popular passages
Page 44 - In any plane triangle, the sum of any two sides is to their difference as the tangent of half the sum of the opposite angles is to the tangent of half their difference.
Page 125 - II. The sine of the middle part is equal to the product of the cosines of the opposite parts.
Page 109 - PROBLEM III. To find the height of an INACCESSIBLE OBJECT above a HORIZONTAL PLANE. 11. TAKE TWO STATIONS IN A VERTICAL PLANE PASSING THROUGH THE TOP OF THE OBJECT, MEASURE THE DISTANCE FROM ONE STATION TO THE OTHER, AND THE ANGLE OF ELEVATION AT EACH. If the base AB (Fig.
Page 41 - To find a side, work the following proportion: — as the sine of the angle opposite the given side is to the sine of the angle opposite the required side, so is the given side to the required side.
Page 243 - Solar Day is the interval of time between two successive transits of the sun over the same meridian ; and the hour angle of the sun is called Solar Time. This is the most natural and direct measure of time. But the intervals between the successive returns of the sun to the meridian are not exactly equal, but depend upon the variable> motion of the sun in right ascension. - The want of uniformity in the sun's motion in right ascension arises from two different causes ; one, that the sun does not move...
Page 117 - A spherical triangle is a portion of the surface of a sphere, bounded by three arcs of great circles.
Page 125 - NAPIER'S CIRCULAR PARTS. Thus, in the spherical triangle A. BC, right-angled at C, the circular parts are p, b, and the complements of h, A, and B. 167. When any one of the five parts is taken for the middle part, the two adjacent to it, one on either side, are called the adjacent parts, and the other two parts are called the opposite parts. Then, whatever be the middle part, we have as THE EULES OF NAPIER.
Page 163 - 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 99 - Now the sum of the areas of the triangles is the area of the polygon, and the sum of the angles of the triangles is the sum of the angles of the polygon.
Page 299 - Twilight begins and ends when the sun is about 18° below the horizon.