package shapes import "math" type Rectangle struct { Width float64 Height float64 } type Circle struct { Radius float64 } func (r Rectangle) Perimeter() float64 { return 2 * (r.Width + r.Height) } func (r Rectangle) Area() float64 { return r.Width * r.Height } func (c Circle) Area() float64 { return c.Radius * c.Radius * math.Pi }