Sym equation to double

I have an equation, y == 319.242, saved as a symbolic variable, and want to use this vlaue as a variable, y. How do I convert the symbolic equation to a variable?

Here's what I have so far. I'm probably doing this the worst way possible, so any help is appreciated.

syms y
theta=60;
r=y/sind(theta);
x=r*cosd(theta);
eqn=y==600-x^2/121;
eqn=isolate(eqn,y);
y=vpa(eqn); %This is where I'm stuck. I don't know how to convert the equation to a double to use in the next equation.
x=y*cotd(theta);
x=vpa(x);
scatter(x,y)

Answer 1

[Star Strider]

There are 2 values for ‘y’, so use solve rather than isolate to calculate them:

syms y
theta=60;
r=y/sind(theta);
x=r*cosd(theta);
eqn=y==600-x^2/121;
% eqn=isolate(eqn,y)
eqn = solve(eqn,y)
y=vpa(eqn); 
x=y*cotd(theta);
x=vpa(x);
scatter(x,y)

.

[Dallin Porter]

Thank you. That's exactly what I needed.

[Star Strider]

As always, my pleasure!

Answer 2

[David Hill]

theta=60;
fun=@(x)600-(x*cotd(theta))^2/121-x;
y=fsolve(fun,300);
x=y*cotd(theta);
scatter(x,y);