to solve this equation -3 cos t = 1 in the interval form 0 ≤ theta ≤ 2n
by using the inverse function of cosine.
-3 cos t = 1
cos t = -1 / 3
then using the inverse function arc cosine or cos^ -1
t = cos ^ -1 ( - 1 / 3 )
t = 1.91 is the value of theta
that is within the range of 0 ≤ theta ≤ 2n
i hope this can help you and feel free to ask for clarifications