10 DEF FN d(a)=a*PI/180:REM convert degrees to radians; all ZX Spectrum trig calculations are done in radians
20 DEF FN i(r)=180*r/PI:REM convert radians to degrees for inverse functions
30 LET d=45
40 LET r=PI/4
50 PRINT SIN r,SIN FN d(d)
60 PRINT COS r,COS FN d(d)
70 PRINT TAN r,TAN FN d(d)
80 PRINT
90 LET d=.5
110 PRINT ASN d,FN i(ASN d)
120 PRINT ACS d,FN i(ACS d)
130 PRINT ATN d,FN i(ATN d)