Problem
Given $\cos t=-\frac{2}{7}$, evaluate the indicated functions. Write your answer as a simplified fraction, if necessary. Part 1 of 3 (a) $\cos (-t)=-\frac{2}{7}$ Part: $1 / 3$ Part 2 of 3 (b) $\cos (t-2 \pi)=\square$
Solution
Step 1 ：Recall that the cosine function is an even function, which means that \( \cos(-t) = \cos(t) \).
Step 2 ：Given that \( \cos(t) = -\frac{2}{7} \), we can conclude that \( \cos(-t) \) should also be \( -\frac{2}{7} \).
Step 3 ：Final Answer: \( \boxed{-\frac{2}{7}} \)
