Answer
Graphical approximation: $\approx-0.65$
Calculator: $\approx-0.65364$
Work Step by Step
For a point on the unit circle, the x-coordinate is $=\cos t$,
the y-coordinate is $\sin t$,
We estimate (see image below)
$\cos 4.1\approx-0.65$
Calculator: -0.653643620864