Solving ODE with multiple initial conditions

So I know people on these forums dont usually like to help people with homework quesitons, but I am genuinely stuck and any hints would be appriciated.

So far I have managed to produce the code bellow;

%Using y for theta and x for t

clear,clc,close;

g=9.81;

L=1;

syms y(x)

Eqn1='D2y+((g/L)*sin(y))=0';

Inits='[y(0)=[0.5;0.8],Dy(0)=[0;0]]';

y=dsolve(Eqn1,Inits);

This code returns an error, previously I could get it to run with a single input for both y(0) and Dy(0), but this would not be enough information for matlab to solve the equation so I would be returned with an error stating that no explicit solutions could be found.

After searching for help else where I was told that my answers had to be inputted as a vector, if this is true where am I going wrong?

Thanks for any help :)