function bh1()
x=[linspace(1,-0.8,150);linspace(1,-0.8,150)];
z=[linspace(9,8.4,150);linspace(9,8.4,150)];
y=[linspace(0,0,150);linspace(1,1,150)];
mesh(x,y,z-2);
hold on
x=[linspace(-0.8,1,150);linspace(-0.8,1,150)];
z=[linspace(8.4,8.1,150);linspace(8.4,8.1,150)];
mesh(x,y,z-2);
hold on
x=[linspace(1,-0.5,150);linspace(1,-0.5,150)];
z=[linspace(8.1,sqrt(9.75)+4.5,150);linspace(8.1,sqrt(9.75)+4.5,150)];
mesh(x,y,z-2);
hold on