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The answer to Cos(1.57079632) (in radians) will give you a clue as to how your calculator does it.

See here [0]

[0] https://www.reddit.com/r/calculators/comments/126st95/cos157...

6.7948900e-9 which has only the first 5 digits correct (if you assume it would have to have been 6.79490 to get 6 digits correct since that is what the correct value rounds to)

Quite well when you realise this comes down to cos(π/2) to which the thing answers correctly: cos(π/2) = 0.

Using HiPER Calc on Android

The number is deliberately close but not the same as pi/2.

See here: https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv017.c...

And you can compare to wolfram alphas result.

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