The angle that a swinging simple pendulum makes with the vertical obeys the equation $(t)=(0\mathrm{.}150$rad$)cos[(2\mathrm{.}85\frac{\text{r}\text{a}\text{l}\text{l}}{s})t+1\mathrm{.}66].$

What is the length of the pendulum?

$0\mathrm{.}83$ m

$2\mathrm{.}02$ m

It cannot be determined from the information given.

$1\mathrm{.}21$ m

$0\mathrm{.}15$ m