Question: How to plot a function under constraint

Hello,

I need some help with plotting the function with varying variables lambda and m ( varying from 0.1 to 1) which subject to the mutual constraint.

My function is:

> d:=(lambda, m) -> (0.1281008386e-3*m*lambda*(20.004936*lambda+21.004936*m+1)^2/(lambda+m)^2+0.1281008386e-3*(21.004936*lambda+21.004936*m-m*(1-lambda))^2/(lambda+m)^2)-(0.2690752038e-2+0.2690752038e-2*m*lambda);

The constraint is:

 > constraint:=(m+lambda)*(4*5.251234-1)*(1-sqrt(lambda*m))-3*lambda>0;

 As this constraint cannot be rewritten in terms of lambda or m,  so I cannot use a handy command like:

plot3d( d(lambda,m), lambda = max(0.1,1/(2+m)) .. min(1), m = 0.1 .. 1);

Does anybody know how to apply this mutual constraint on the function so that the area satisfying this constraint will be plotted?

Can it be inserted in the general plot command plot3d (d (lambda,m), lambda=0.1..1, m=0.1..1); ?

Thank you very much in advance,

Olga