Drawing Czechia flag with Java AWT

CzechiaFlag.java

import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Frame;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

class CzechiaFlag {
    static class CzechiaFlagComponent extends Component {
        public void paint(Graphics g) {
            // Get the width and height of the frame
            int frameWidth = getWidth();
            int frameHeight = getHeight();

            int middleHeight = frameHeight / 2;

            g.setColor(Color.white);
            g.fillRect(0, 0, frameWidth, middleHeight);

            g.setColor(Color.red);
            g.fillRect(0, middleHeight, frameWidth, middleHeight);

            // get radius (a^2 + b^2 = c^2)
            int trianglePoint = frameWidth / 3;
            double radius = Math.sqrt(Math.pow(trianglePoint, 2) + Math.pow(middleHeight, 2));
            int radiusInt = (int)radius;

            // get angle
            double angle = Math.atan2(middleHeight, trianglePoint);
            double angleDegrees = Math.toDegrees(angle);
            int angleInt = (int)angleDegrees;

            int circleSize = radiusInt * 2;
            int xOffset = trianglePoint - radiusInt;
            int yOffset = middleHeight - radiusInt;

            // draw arc
            g.setColor(Color.blue);
            g.fillArc(xOffset, yOffset, circleSize, circleSize, 180 - angleInt, angleInt * 2);
        }
    }

    public static void main(String[] args) {
        Frame innerFrame = new Frame("czechia flag");
        innerFrame.setSize(400, 300);

        innerFrame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent we) {
                System.exit(0);
            }
        });

        innerFrame.add(new CzechiaFlagComponent());
        innerFrame.setVisible(true);
    }
}