These are two examples of kuspuks worn by females. The thing about making these outfits is that each one is cut individually to fit the person who is wearing it. You actually hold the material up against the person to figure out how wide and long to cut the base part which is the main body of the kuspuk. Two more rectangle are cut into trapezoids to make the sleeves. Two small rectangles for cuffs. The only pieces that are really cut with curves are the front pocket pieces and the hood. Even the skirt is made of several rectangles sewn together and gathered.
One lady told me that when you sew like this, you are making the garment so it is proportional to the persons body and it will look good on them.
There is a series of math books out there called "Math in a Cultural Context". Jerry Lipka up at the University of Fairbanks worked with many, many people to create some wonderful math units that could be used from lower elementary up to high school. Topics include place value, probability, navigation, geometry, and other good topics. I've used several in my classroom and they work well.