Find the length of line AC use that length to find the length of line CD

Atrail mix recipe includes granola oats and almonds there are 135 calories in a 1/= cup serving of the trail mix .how many calories are in2 cups of trail mix?

One expression below in undefined, and the other expression has a well defined value. which expression is undefined and explain why it has no value. which expression is defined? what is the value of that expression and how do you know? what is a different expression using a trig inverse function that is also undefined?

Can some one me with these questions