Unrecognized variable Using solve command

It keeps giving “unrecognized function or variable ‘theta’

Answer 1

[Star Strider]

Perhaps:

syms theta

just after the ‘outputs’ comment would help.

Also MATLAB is case-sensitive, so change:

Angle = 10;

to:

angle = 10;

The vpa.function could also be helpful.

.

[Walter Roberson]

if theta is symbolic and angle is numeric then assignment to

Eq340(theta, angle)

would be an error.

I say that you should

syms theta angle

and change the Angle in Eq340 to angle

After that the last statement would become

theta = subs(S, angle, Angle)

Question: are you sure that you want to be working with 10 radians? It looks to me more likely that you should be using sind(angle) instead of sin(angle)