2D Equations

The symbol is composed with following 4 equations.

* Wave - Ying and Yang

y1(x)= +sqrt(2^2-(x-2)^2)

y2(x)= -sqrt(2^2-(x+2)^2)

* Circle 
   x^2 + y^2 = r^2

   r = 4

y3(x)= +sqrt(4^2-x^2)

y4(x)= -sqrt(4^2-x^2)

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