I am sure if you knew a few lengths of the shadows. basically situated on triangles with at least one 90° angle, with the help of some trigonometry, you can discover all the other necessary measurements. At least that is what Pythagoras did for his living. The maths teachers at my school were convinced that we should all become children of Pythagoras. I remember the square on the hypotenuse of a right triangle was equal to the sum of the sides of the two adjacent sides, thanks to Danny Kaye and his song. However it really works, I had to do it enough at school.

As far as equations are concerned, I did five years of them in my maths lessons at school. I can still apply the idea, although at the age of 77 no longer as good as it was. The idea is to prove something with equating the same thing on both sides of the = if you know what I mean – of course not, we all have computers today.