Python 3.2.2中的打印语句中的语法错误无效

Question

当我试图运行我的程序并且最后一行中的打印以红色突出显示时，出现语法错误。我不明白为什么会出现语法错误。

# 6. Calculate the radius of the circle using the 
#  distance formula on a given point and the center 
r = math.sqrt((a-x)** + (b-y)** 

# 7. Output to the shell the location of the center 
# of the circle 
print("The center of the circle is at (",x,",", y,")",sep="") 

# 8. Output to the shell the radius of the circle    
print("The radius of the circle is " , r) 

Answer 1

r = math.sqrt((a-x)** + (b-y)** 

大概应该是

r = math.sqrt((a-x)**2 + (b-y)**2) 

缺少的结束括号使摊开以下系中的表达。在最后一行调用print()之前，该表达式符合Python的语法（即使这看起来令人惊讶）。