We are like the only 6 people on the planet who care about such things. Even my fashionista people don't understand how trigonometry relates to high heels. Few, if any, have any concept of the height of the heels they wear or don't wear.
Until very recently, I just used the actual heel measurement in our conversation here. I figured my size 40 was close enough--and it probably is for 99.9% of the people in the world. For this challenge, however, actual steepness actually matters, so I changed my way of stating it, in order to have and apples to apples comparison.
I can remember a former member here, years ago, saying he'd spent the entire day in 4 inch heels. Pretty impressive until you actually saw the shoes. In his size, they were almost like kitten heels!