1. Desmos graph:
    https://www.desmos.com/calculator/zmp5vvet1g
  2. My StackExahange post (1):
    https://math.stackexchange.com/questions/2653980/dog-bone-shaped-curve-xx-yy
  3. My StackExahange post (2):
    https://math.stackexchange.com/questions/2655328/area-of-region-in-the-dog-bone-shaped-curve-xx-yy