APr. c] 



APPENDIX 



519 



Or-Tlprwit Chord = 2 rad \ Ven AiQ + |) - 1 |- 



Fig. 119. 



Let C AB = ^, the. angle whose chord is retjuired. 

 Ax any radius A = r, describe arc C B. 

 Join C B, then B is Chord required. 

 Bisect B C in D ami join A D. 



Then DAB =i. 



2 



Now DB = AB, SiiiDAB 

 = r.Sin|, 



hntBC=2DB; 

 ABC = 2 r. Sin I (a). 



Bi!t Versine - = 1 — Cos _ ; 

 .'. Versine (^90 + I") - 1 - Cos (90 + 



= 1 + Sin I 



:. Sin I = Vers ( 90 + |) 

 Substituting this in («) we get 



EC = 2r jVers^GO + M - 1 ^ 



