# A Treatise on Plane and Spherical Trigonometry: With Their Most Useful Practical Applications

Cadell and Davies, 1818 - 438 „‰ «·’ðÕ«

### „« ÌÞÊ·Â «·‰«” -þ «»… „—«Ã⁄…

·„ ‰⁄À— ⁄·Ï √Ì „—«Ã⁄«  ðÌ «·√„«þ‰ «·„⁄ «œ….

### „Þ«ÿ⁄ „‘ÂÊ—…

«·’ðÕ… 1 - 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.˛
«·’ðÕ… 9 - ... for the second term, and the greater for the first ; and in either case multiply the second and third terms together, and divide the product by the first for the answer, which will always be of the same denomination as the third term.˛
«·’ðÕ… 352 - C' (89) (90) (91) (92) (93) 112. 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.˛
«·’ðÕ… 386 - The sum of any two sides of a spherical triangle is greater than the third side, and their difference is less than the third side.˛
«·’ðÕ… vii - The rectangle contained by the diagonals of a quadrilateral inscribed in a circle is equal to the sum of the two rectangles contained by its opposite sides.˛
«·’ðÕ… 17 - To find the other side: ó as the sum of the two given sides is to their difference, so is the tangent of half the sum of their opposite angles to the tangent of half their difference...˛
«·’ðÕ… 20 - As the base or sum of the segments Is to the sum of the other two sides, So is the difference of those sides To the difference of the segments of the base.˛
«·’ðÕ… 8 - C 76∞ 45i'. 2. Given the three sides 58, 39, and 46 ; to find the angles. 173. Any right lined figure whatever, whose sides and angles are given, may be constructed, by laying down the sides from a scale of equal parts, and the angles from a line of chords. Ex. Given the sides AB (Fig.˛
«·’ðÕ… 3 - Sine, or Right Sine, of an arc, is the line drawn from one extremity of the arc, perpendicular to the diameter which passes through the other extremity. Thus, BF is the sine of the arc AB, or of the supplemental arc BDE.˛
«·’ðÕ… 409 - From the logarithm of the area of the triangle, taken as a plane one, in feet, subtract the constant log 9-3267737, then the remainder is the logarithm of the excess above 180∞, in seconds nearly.* 3.˛