We don't know what the answer choices are!!
Answer:
<em>(a). - 1 ; (b). y = - x + 11</em>
Step-by-step explanation:
(1, 10)
(6, 5)
<em>(a).</em> <em>m</em> =
=
= <em>- 1</em>
<em>(b).</em> y - 5 = - 1(x - 6)
<em>y = - x + 11</em>
This question is asking "Where does cosine equal

?"
Based on our unit circle values and the domain of the cos^{-1} function, we see that at 30 degrees, or

, cosine is equal to

.
Therefore, f(c) = 3c+5
OPTION B is the correct answer