pre calc
posted by jim .
sin 20 pi
cos 9 pi
cos 13pi/2
sin(17 pi0
are all of these undefined?

sin 20 pi = sin (2 pi*10) = sin 2pi = 0
cos 9 pi = cos (8 pi +pi). That is 4 times around the circle plus pi so it is really cos (pi) = 1
No, they are not undefined.
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