Java中的Math.sin（）函数问题，请大家看看

Question

import java.applet.Applet;
import java.awt.Graphics;

public class testCircle extends Applet {
public void paint(Graphics g){
g.drawRect( 0, 0, 100,100);
g.drawOval(0, 0, 100, 100);
g.drawOval(48, 48, 4, 4);
g.drawLine(50, 50, (int)(50+40*Math.cos((30/180)*Math.PI)), (int)(50+40*Math.sin((30/180)*Math.PI)));
}
}
为什么会是这样的，真实的情况应该是那条线是向右下偏的呀？求大神解释(https://img-ask.csdn.net/upload/201603/09/1457534436_745782.png)

Answer 1

30/180等于0，所以就成水平的了，换成30.0/180，