1 #include "Circle.h" 2 Circle(double radius)3 Circle::Circle(double radius) : radius_(radius) {} 4 area() const5 double Circle::area() const { 6 return 3.141 * radius_ * radius_; 7 } 8 perimeter() const9 double Circle::perimeter() const { 10 return 3.141 * radius_; 11 }