A man of 2m height stands on the shore in Ouchy, exactly on the water line. His girl friend was on a shopping trip in Evian and is now at the shore in Evian with her just purchased new red stiletto-heeled shoes, again just on the water line. Is the man able to admire the shoes of his girl?

He has powerful field glasses at his disposal: hence no problem in this respect. But how about the curvature of the earth and thus the water surface. Is it noticeable over the relatively short distance. He is nevertheless quite tall: 2m.

Suppose he can indeed not see her shoes. Could he then at least see her new hairdo? Because she also went to a hair salon. Or asked in a different way: how tall would she have to be for him to see her hair?

You can simply guess and tell me your conjecture by clicking on "Email" in the menu on the left. But, of course, you could also do some maths. Using the Pythagorean formula for a right triangle will do the trick. But note that you have to calculate fairly accurately, because of the large size difference of the 12km distance and the earth radius of 6371km involved.

Have fun! I am looking forward to your results.

(Illustration of the principle. The horizontal and vertical scales are obviously not shown correctly)   My granddaughter Rebecca drew the pictures on the right and on the left     Blog                          Other Quiz