Hi guys, drawLine() doesn't require the points to vary. In fact drawLine(10,10,10,10) would simply result in a point being drawn.

It's Math.PI because all constants, as per the Java convention, are in uppercase. He isn't using degrees though so there isn't a need to convert between degrees and radians; Math.sin(x) where x is an angle measured in radians. The conversion is degrees * PI/180 btw.

He isn't drawing a circle and his approach is almost correct...

What you need to remember Jahan, is that sin graphs have an amplitude of 1 unit. That is, your y value is going to range between -1 and 1 (at least in this case). Since you're dealing with a continuous function, your (int) conversion is going to give you values of either -1, 0 or 1 and this is not what you want. I suggest multiply the double value you get from the sin method with some constant before you convert the value to int. I hope this makes sense? This constant should be used to scale your x value of the Cartesian plane to pixels so perhaps 1 x unit is 10 pixels.

Moreover, your graph isn't going to be drawn on the axises you created because your (x, y) pairs in the drawLine() method don't match the values of your axises. It's not a difficult thing to do, but it does require you to think of the differences between a Cartesian plane and the pixel co-ordinate system you're using on your computer.