Circle animation not working

ContentView.swift

struct ContentView: View {
    @State var angle: Float = Float.pi / 2.0
    
    let radius: Float = 200
    
    var body: some View {
        ZStack {
            Circle()
                .strokeBorder(.black, lineWidth: 2)
                .foregroundColor(.clear)
                .frame(width: CGFloat(2*radius), height: CGFloat(2*radius))
                .position(x: 400, y: 400)

            Circle()
                .frame(width: 50, height: 50)
                .foregroundColor(.blue)
                .position(x: CGFloat(400 + radius * cos(angle)), y: CGFloat(400 - radius * sin(angle)))
        }
        .frame(width: 800, height: 800)
        .background(.white)
        .onAppear {
            withAnimation(.easeInOut(duration: 2.0)) { // withAnimation tells that states modified in closure are animated
                angle = -Float.pi / 2.0
            }
        }
    }
}