First problem:
cos (theta)=1
Using the inverse cosine function, you get theta = 0.
Now we find tan 0 = 0
cot(theta) = 1/tan(theta) = 1/0
Division by zero is undefined, so the answer is d. undefined
Second problem:
cos (theta)=1
Use the inverse cosine function.
theta = 0°
Answer: c. 0°