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

1 Answer
Oct 21, 2015

cos(8pi)=1

Explanation:

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