[Title: COSINE LAW]
'COS
"S=0<>A(deg)": ?->G: 
0<>G=>Goto 0: 
 \sqrt(N\^2+O\^2-2NOcos M(deg)): 
 Goto 1: 
Lbl 0: 
cos \^-1((N\^2+O\^2-M\^2)/2NO): 
 Lbl 1