Calculator not working when hidden field

I’m facing the following problem: I have a Select with 4 options, the first of which is “Select option…”. When the first option is selected, the 4 input fields are hidden with the .hide() function, when the user selects option 1, only inputs 1, 2 and 3 are shown, and when the user selects option 2, fields 1, 2, 3 and 4 are visible. The problem is that when field 4 is hidden in option 1 the calculations are not performed and I don’t understand the reason. Can you help me?

Obs.: I use Math.cos and Math.sin functions