Inverse Trig Calculator

This covers the three inverse trigonometric functions almost no calculator has a key for: arcsec, arccsc and arccot. Enter a value and it returns the principal angle in degrees, radians, multiples of pi, gradians and degrees-minutes-seconds, together with the identity it used, a check by the forward function, and every other angle that shares that value. Arcsec and arccsc reject anything strictly between -1 and 1, because secant and cosecant never land there. Arccot has two competing range conventions that disagree by 180 degrees for negative arguments, so both answers are printed. Arcsin, arccos and arctan each have their own page.