You can do 5+5+10, 6+6+8, 9+9+2, 4+4+12, 3+3+14, 2+2+16, 1+1+18. I believe these are all of them, so there are 7 ways.
The statement above is true. Polar equations indeed can describe graphs as functions, even if when the equations in the rectangular coordinate system are not one of the functions. Polar equations can be graphed accurately using hands by using the Polar Coordinate System.
The Greek mathematician who wrote the most definitive text on geometry, one that is still referred to today is Euclid. Euclid of Alexandria is also called "Father of Geometry". He was a great Greek mathematician. Euclidean geometry is still widely taught in schools and colleges. I hope the answer comes to your help.