made circle

circle.py

@@ -1,20 +1,30 @@
 from sympy import *
-
-class semicircle:
-    def __init__(self,x,y,r,upper=False):
-        if upper:
-            self.coef = 1
-        else:
-            self.coef = -1
-
-    self.x = x
-    self.y = y
-    self.r = r
-    self.expr = simplify(self.y + self.coef * sqrt(r**2 -
-
+_x = symbols('x')
+_y = symbols('y')
 class circle:
     def __init__(self,x,y,r):
         self.x = x
         self.y = y
         self.r = r
-    
+
+    def get_expr(self):
+        return self.r**2 - (pow(_x-self.x,2) + pow(_y-self.y,2))
+
+    def get_x(self,y):
+        expr = self.get_expr()
+        expr = expr.subs(_y,y)
+        return solve(expr,_x)
+
+    def get_y(self,x):
+        expr = self.get_expr()
+        expr = expr.subs(_x,x)
+        return solve(expr,_y)
+
+    def get_diff(self,dydx=True):
+        expr = self.get_expr()
+        if dydx:
+            return expr.diff(_x)
+        else:
+            return expr.diff(_y)
+if __name__ == "__main__":
+    unit_circle = circle(0,0,1)