How do you find the exact value of cos 8(pi)?

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Answer 1 · 2015-10-21T20:47:48

#cos(8pi)=1#

If we go once around the circle we have gone through an angle
#2pi#

#cos(2pi)=1#

If we go around another time we have gone through and angle of
#4pi#

The third time the angle is #6pi#

Finally after going around 4 times we are at #8pi#

Remember cosine is a cirlular function. Since we are back where we started after #4# complete revolutions

#cos(8pi)=1#