Solving the equation in Simulink

I need to solve an equation in Simulink. I've created an Embedded MATLAB Block and tried using 'solve' command this way but its not working.

function sol = Solvesys(a,b,c)

syms a b c ; eqn = ((a*b)/(2)) == (c (2)* z) + (c (1) * sqrt(8-z^2)); sol = solve (eqn,z);

I want to solve it for z where a,b and c are my inputs from other simulink blocks. Can anybody guide pl?