Solve a symbolic equation with a Sin function?

Questions
,
1

Hello, guys.

In physics problem, in order to extract the parameter, I am trying to simultaneously fit multiple ‘frequency’ formulas with experimental data after solving ‘Equation1’ symbolically. But I think that the mathematica cannot solve ‘Equation1’ properly as this equation cannot be solved analytically. How should I modify this code? -_-a. Could you help me out ?

For making you understand better,
In the attached code,

[Theta]H : independent variable (x)

[Theta]eq : obtained value at given (x)

Freq0,1,2 : values to be fitted

Dexc : values that I want to extract.

Thank you in advance. If you think that there are some points unclear, please let me know.

Test.nb (19.4 KB)

2

Among other problems, there is a mix of radian and degree measurements. This messes up an inequality or two. Also you probably will want delayed assignment for the functions that require numerical arguments.

3

Thanks for the reply.

I made all units same again. But the sample error messages are there.

As long as two arguments are in Sin function, it is hard to be solved, no..?

Is there any way to circumvent this…? -_-a

Thank you,