How to solve a non linear equation in simulink?

I am trying to solve the following equation for the value of phi in simulink. All other parameters are known.

I am using the Algebraic Constraint block in Simulink but, I am getting an error as follows.

Algebraic state in algebraic loop containing 'Solving phi/Subsystem/Algebraic Constraint/Sum' computed at time 0.0 is Inf or NaN. There may be a singularity in the solution. If the model is correct, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)

I am using a step size of 10e-06 and an initial guess as 4 degrees. How can I solve this equation? Or what is the equivalent of lsqnonlin which I can use in Simulink?