Find angle between two fitted planes

I want to find the angle between two planes which have been fitted to a set of points (x,y,z); here, x and y are pixel position and z is the intensity value for position (x,y). I used the fit function as below:

For Image-1:

Image1 = double(imread('Image1.png'));
x = 1:size(Image1,1);
y = 1:size(Image1,2);
z= Image1;
[xo,yo,zo] = prepareSurfaceData(x,y,z);

For Image-2:

Image2 = double(imread('Image2.png'));
x1 = 1:size(Image2,1);
y1 = 1:size(Image2,2);
z1= Image2;
[xg,yg,zg] = prepareSurfaceData(x1,y1,z1);

Now, I fit a plane to these image points as following:

% fitted plane for the first image
fc =fit([yo,xo],zo,'poly10','Normalize','on','Robust','Bisquare');
% fitted plane for the second image
fg = fit([yg,xg],zg,'poly10','Normalize','on','Robust','Bisquare');

I plot these fitted planes as following:

figure
h1=plot(fc);
set(h1(1),'Edgecolor','none')
set(h1(1),'FaceAlpha','0.99')
set(h1(1),'FaceColor','green')
hold on
h2=plot (fg);
set(h2(1),'Edgecolor','none')
set(h2(1),'FaceAlpha','0.99')
set(h2(1),'FaceColor',[0.5 0.5 0.5])

hold off

I would like to measure the angle between the fitted planes fc and fg. Could you please suggest how can I measure the angle between them?