549.sagews

# Generally a hyperbola is not a function, and so will not plot easily.  But 
# one form of it is a function, for easy plotting use xy = c.

# (x^2/a^2) - (y^2/b^2) = 1
x = var('x');
a = 1; b = 1;
y1 = plot(sqrt((x^2)*b/a - 1),-5,-1);
y2 = plot(sqrt((x^2)*b/a - 1),1,5);
y3 = plot(-(sqrt((x^2)*b/a - 1)),-5,-1);
y4 = plot(-(sqrt((x^2)*b/a - 1)),1,5);
show(y1+y2+y3+y4,-5,5,-5,5);

# xy = c
c = 3;
y = plot(c/x,-5,5);
show(y,-5,5,-5,5);