How tall is a building that casts 67-ft shadow when the angle of elevation of the sun is 30 degrees

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?

Whats the name of the vertical axis

What is the result of the following division?