Apple - Inverse trigonometric functions in Calculator

Hit the shift key in Calculator in older versions of OS X to get all inverse trigonometric but also some other functions:

In El Capitan it works with the "2nd" button (the real keyboard's shift key should work as well):

To calculate atan() and atand() in Calculator under OS X El Capitan, do the following…

1. Open Calculator.

2. Press command2 on the Mac’s keyboard, to show the Scientific Calculator.

3. To calculate inverse trigonometric functions, click the 2^nd button (left side, second row, first button) on the calculator (or you can press and hold the shift key on the Mac’s keyboard during a given operation) in order to change the tan button to display as: tan ^-1

4. To change between calculating degrees and radians, toggle the button in the lower left corner of the Scientific Calculator between Deg and Rad.

   • The default is to calculate degrees and the Rad button is shown.
   • To calculate radians, click the Rad button so it shows Deg. Note that Rad also appears in the left side of the main display.

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Result for atand(1):

Result for atan(1):