Radio Shack TRS-80 PC-3 Owner's Manual page 177

1 ASN numeric expression
ASN is a numeric function which returns the arcsine of the numeric argument. The arcsine is the angle whose sine is equal to the
expression. The value returned depends on whether the PC-3 Computer is in decimal degree, radian, or gradient mode for angles.
ASN .5 is 3(3 in the decimal degree mode.
1 ATN numeric expression
ATN is a numeric function which returns the arctangent of the numeric argument. The arctangent is the angle whose tangent is
equal to the expression. The value returned depends on whether the PC-3 Pocket Computer is in decimal degree, radian, or gradient
mode for angles. ATN 1. is 45 in the decimal degree mode.
1 COS numeric expression
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