2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/59504Fermat Last Theorem, which inspired mathematicians during 300 years, is proved by Andrew Wiles. Even among mathematicians there is a narrow circle of specialists, who can read this proof and understand all details. Is it a reason for pessimism? No, since arithmetics if entire numbers contains broad variety of problems with a simple statement, which might be not less intricate. One of them arises in elementary geometry.AmSTeX, 10 pages, amsppt styleGeneral MathematicsAlgebraic Geometry11D09, 97U40text