GEOGRAPHIC TABLES AND FORMULAS. 
(SECOND EDITION.) 
Compiled by S. S. Gannett. 
RTTTjES for SOI.ITTIOK OF RIGHT-AlSTGIuED TRIA:N^GLES. 
The ' ' parts " of the figures are — 
H = hypothenuse, 
P = perpendicular, 
B=base, 
and the six circular functions of the angle a at the base of the triangle. 
Secant 
! Cosecant —\ 
\ Tangent \ 
Sine 
Cosine 
/ 
/ 
Fig. 1.— Solution of right-angled triangles. 
Rule I. The product of two opposite parts = 1, .*. either is the 
reciprocal of the other. 
Example: Tan a X cot <t = 1, tan ^ = ^.^^f^' 
Rule 11. Each part^adjacent part divided by the following part, 
.*. each part = thc product of the adjacent parts. 
Example: bmr^= .. . ^ ... ' sin <3^=-tt' 1>=i1Xcos ol. 
cot OL 
H 
