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) $\cos (t - 2 π) = ◻$

Answer

Expert–verified

Hide Steps

Answer

Final Answer: $- \frac{2}{7}$

Steps

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: $- \frac{2}{7}$