I'm getting wrong ans on test case 3. Can someone please give a hint?

Here's my solution in Java:

FastReader sc = new FastReader(System.in);
        double a = sc.nextDouble();
        double r = sc.nextDouble();
        double ans;

        if (r <= a / 2) {
            ans = Math.PI * r * r;
        } else {
            double angle = (2 * Math.PI) - (8 * Math.acos(a / (2 * r)));
            ans = (r * r * angle / 2) + (2 * a * Math.sqrt(r * r - a * a / 4));
        }

        System.out.println(String.format("%.3f", ans));