GEOGRAPHIC TABLES AND FORMULAS. 
Compiled by S. S. Gannett. 
RTTLFS FOR SOLUTION OF RIGHT-ANGLED TRIANGLES. 
The "parts" of the figures are — 
H = hy pothenuse, 
V = perpendicular, 
B=base, 
and the six circular functions of the angle oc at the base of the triangle. 
Secant 
Cosecant -\ 
Fig. 1.— Solution of right-angled triangles. 
Rule I. The product of two opposite parts = 1, .'. either is the 
reciprocal of the other. 
Example: Tang oc x cot a = 1, tang oc — , ^ . 
Rule II. Each part = adjacent part divided by the following part, 
. *. each part = the product of the adjacent parts. 
cos oc I* 
Example: Sine a = — r — , sine oc — -ff, B = H X cos a. 
