10 LET diam=2*6372.8
20 LET Lg1m2=FN r((-86.67)-(-118.4))
30 LET Lt1=FN r(36.12)
40 LET Lt2=FN r(33.94)
50 LET dz=SIN (Lt1)-SIN (Lt2)
60 LET dx=COS (Lg1m2)*COS (Lt1)-COS (Lt2)
70 LET dy=SIN (Lg1m2)*COS (Lt1)
80 LET hDist=ASN ((dx*dx+dy*dy+dz*dz)^0.5/2)*diam
90 PRINT "Haversine distance: ";hDist;" km."
100 STOP
1000 DEF FN r(a)=a*0.017453293: REM convert degree to radians