Question

if cos t = -2/5 what does cos(2pi-t) ?

Answer 1

cos(2pi-t)=-cost=2/5

Answer 2

I thought that too, but apparently it equals -2/5 in my book -_-

Answer 3

@myininaya do you know ?

Answer 4

@amistre64 ?

Answer 5

smfh i think my book got it wrong ? =/

Answer 6

\[\cos(2\pi-t)=\cos(2\pi)\cos(t)+\sin(2\pi)\sin(t)=1 \cos(t)+0\sin(t)=1\cos(t)=\cos(t)\]

Answer 7

book isn't wrong in this case