Help



Hi,
I would like to integrate yin or yang...
As I am not an expert, I can't solve the 1/2 circle on the right side ?
Is there a way of doing it ?
thank you and best wishes for 2012,
regards
--------------------that's what I have done 
yet------------------------------

f(x):= sqrt(4-x^2)$g(x):=sqrt(4-x^2)$p(x):=sqrt(1-x^2)$
o(x):= -sqrt(1-x^2)$n(x):= -sqrt(4-x^2)$m(x):=-sqrt(4-x^2)$
wxdraw2d(user_preamble = ["set size ratio 1","set zeroaxis"],xaxis = 
true, yaxis = true,
/*filling*/
          fill_color = grey,
          filled_func =(f(x),x,0,2),
          filled_func =(g(x),x,-2,0),
          filled_func =(o(x-1),x,-2,0),
          color = red,explicit(p(x+1),x,-2,0),
          color = red,explicit(n(x),x,-2,0),
          color = red,explicit(m(x),x,0,2),
          filled_func = false,
/*unfilling*/
          filled_func = false,
/*NE*/   color = black,explicit(f(x),x,0,2),
/*NO*/   color = red,explicit(n(x),x,-2,0),
/*1/2SE*/color = black,explicit(o(x-1),x,0,2),
/*SW */  color = black,explicit(g(x),x,-2,0),
/*1/2NO*/color = red,explicit(p(x+1),x,-2,0),
/*SE*/         color = red,explicit(m(x),x,0,2))$