What if for step 1 you picked (6,3)?

Volume of a cylinder with a radius of 13 in and height of 30 in

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?

On a architect's drawing of a house, 1 inche representa 1.5