I’ve written about the diagonals of an isosceles trapezoid before.
When we practice “I can look for and make use of structure”, we practice: “contemplate before you calculate”.
We practice: “look before you leap”.
We ask: “what you can you make visible that isn’t yet pictured?”
We make mistakes; the first auxiliary line we draw isn’t always helpful.
Or sometimes we see more than is helpful to see all at one time.
Even with the same auxiliary lines, we don’t always see the same picture.
We learn from each other.
And so the journey to make the Math Practices our habitual practice in learning mathematics continues …