# A Treatise on Plane and Spherical Trigonometry

Leach, Shewell & Sanborn, 1894 - 193 pàgines

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Pàgina 32 - 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.
Pàgina 98 - The logarithm of any power of a number is equal to the logarithm of the number multiplied by the exponent of the power.
Pàgina 56 - The sum of the angles of a spherical triangle is greater than two and less than six right angles ; that is, greater than 180° and less than 540°. (gr). If A'B'C' is the polar triangle of ABC...
Pàgina 55 - Cot. D. 1". Tan. M. 40° 139° 130° 49° M.] Sin. D. 1".
Pàgina ii - The foregoing method is based on the assumption that the differences of logarithms are proportional to the differences of their corresponding numbers, which, though not strictly accurate, is sufficiently exact for practical purposes.
Pàgina 49 - ... cos a = cos b cos с + sin b sin с cos A ; (2) cos b = cos a cos с + sin a sin с cos в ; ^ A. (3) cos с = cos a cos b + sin a sin b cos C.
Pàgina 98 - I. The logarithm of a product equals the sum of the logarithms of the factors.
Pàgina 60 - Rules are . (1) The sine of the middle part equals the product of the tangents of the adjacent parts.
Pàgina v - In searching for the next less (or greater) logarithm, attention must be paid to the fact that the functions are found in different columns according as the angle is below or above 45°. If, for example, the next less logarithmic sine is found in the column with
Pàgina 30 - In any triangle the square of any side is equal to the sum of the squares of the other two sides minus twice the product of these two sides and the cosine of their included angle.