Anyone need help with a subject mark me brainlist

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?

In the diagram, the measure of angle 9 is 85° which angle must also measure 85°?

Lisa has three classes that each last 50 minutes. what is the total number of minutes of the three classes