name 3name name3 _name name_3 name&3 True
a=float(input("please input a:"))
b=float(input("please input b:"))
c=float(input("please input c:"))
if __________________________:
p=(a+b+c)/2
s=(p*(p-a)*(p-b)*(p-c))**0.5
print("三角形的面积是:",s)
else:
print("构不成三角形")