Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

164 moleswobth’b pocket-book F = A force acting in one direction, y — „ „ in another direction. P — Resultant force of F and f combined. A = Angle of direction of F with f a — Angle of P with F. P = v'^V+7r+(2F/cos. A). p — J pa + yi _ (2 F/ cos. 180° - A) when A exceeds 90°. . /sin. A • Psin. a Sin. a —, p • f gtø a By Parallelogram of Fobces. Measure by any scale on each line their respective units of force, and complete the parallelogram; the diagonal repre- sents the force and direction of the resultant. In the diagram two forces, A B = 10 tons and BD = 1 tons, give a resultant of BC = 13*8 tons.