Important Formulas in This Chapter

Heres a reminder of the two main formulas introduced in this chapter.

Coordinate rotation:

 x1 = Math.cos(angle) * x     Math.sin(angle) * y; y1 = Math.cos(angle) * y  +  Math.sin(angle) * x; 

Reverse coordinate rotation:

 x1 = Math.cos(angle) * x  +  Math.sin(angle) * y; y1 = Math.cos(angle) * y     Math.sin(angle) * x;