I do not understand what you are trying to do.

I think that after delay(), you want:

Because you didn't set the right variables?

How can you expect to have reliable answers on random code? Copy / paste is a good way to put code here...
Note that delay() is probably the wrong solution to your problem, anyway. It is so much a wrong solution that it is prone to disappear from Processing in the next version!

I didn't copy and paste because it was only a segment of the code that I was having trouble if I would have pasted the whole thing it would have been needlessly complicated. I should have had the variables set correctly that was a sloppy mistake and I have no excuse for that. I obviously know its the wrong solution because I asked this question to begin with acknowledging that there was a problem. Obviously the problem is with the delay and obviously its wrong, I'm trying to learn and would like to know why its wrong. Telling me how wrong it is doesn't help me at all. If you don't know why its wrong don't comment.You wouldn't like it if someone acted this way to you so knock it off. 

Hello,

some more remarks.

I made the change that "boom" now gets an initial value > 0 in setup().
Without this, boom would be 0 (zero) and thus your line would go from 0,0 to 0,0 (boom*cos(phi); being always zero).

I also changed the beginning of your line-statement: instead of 0,0 I put width/2, height/2, so the circle is in the middle of the screen and not in the upper left corner, because then you can't see the circle most of the time (it's outside the screen).

For the second two arguments (arguments 3 and 4) of line ()  I also put width / 2 + boomX, height / 2 + boomY instead of boomX, boomY alone, because boomX and boomY is the difference between the center of the circle and its circumference. So it is wise to add the center of the circle to them to really get to the circumference .

Delay stops the machine and has therefore unwanted side effects. When you keep on running without delay(), draw is called again and again, so it's a loop. Therefore you can set your variables at the end and compare them at the beginning of draw() with the actual values of mouseX and mouseY. When you need a delay, you better use a Var OldTime, store the time in it and then keep on running until OldTime+YourDelayTime=NOW. For a better explanation, please see http://wiki.processing.org/w/I_display_images_in_sequence_but_I_see_only_the_last_one._Why%3F

Sorry for all the hassle. This is good forum and you get good help here. So keep going!

Greetings, Chrisir