How do I draw an half Circle in opengl

I use this method which works perfectly to draw a full circle(might be typos in code text I wrote from memory):

drawCircle(GLAutodrawble drawble){
   GL gl = drawble.getGL();
   gl.glTranslatef(0.0f,0.0f,-7.0f);
   gl.glBeginf(GL_LINE_LOOP);
   gl.glColorf(0.0f,0.0f,0.0);
   final dobule  PI = 3.141592654;
   double angle = 0.0;
   int points = 100;
   for(int i =0; i < points;i++){
     angle = 2 * PI * i / points;
     gl.glVertexf((float)Math.cos(angle),(float)Math.sin(angle));
   }
   gl.glScalef(1.0f,1.0f,0.0f);
   gl.glEnd();
 }
 

I want to use the same priciples to make method to make a half circle, I don't get my head around what I should do with the cos sin stuff. Can anyone take a look and help me.

Thanks goes to all that thakes a look at the problem!

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