Angle of the close (on the close of the bar) from 1 bar to n bars ago

This requires knowledge of mathematics (trigonometry) and experience in mql4. 

On the close of the bar, I want to calculate the angle from the last bar to some bar n bars ago. This on a window. I also want to measure the vertical distance between these 2 points. So the custom indicator would have 2 buffers, only displaying the angle. This does not work if you do it on the standard charts: it only makes sense if you do it in pixels, not in time units and pips: so the size of the units on the vertical axis equal the size of the units on the horizontal axis. This can be done in MT4 by pushing F8 , and on the Common tab checking the box Scale fix One to One. So on the close of the bar, record the angle from the last close to the close x bars ago and measure that vertical distance.