https://www.codecademy.com/en/courses/spencer-sandbox/5/4?curriculum_id=506324b3a7dffd00020bf661#

I can't seem to figure out this exercise. It keeps mentioning this error message:

Oops, try again. Your code caused a TypeError when trying to call .perimeter(). Make sure you have properly defined the perimeter method. Use the .area() method as a guide. Here's the error message: TypeError: c.perimeter is not a function

```
Replace this line with your code.
function Circle (radius) {
this.radius = radius;
this.area = function () {
return Math.PI * this.radius * this.radius;
};
// define a perimeter method here
function perimeter(radius){
return (2*Math.PI)*radius;
}
}
```