Frame notable products with feet

Function

Intended for experimental study, mathematics laboratory and carrying out mathematical experiments on: Mathematics. Algebra. The remarkable square product of the sum of two terms. Expressions, called remarkable products. The remarkable square product of the sum of two terms. Proof of the truth of the rule of the remarkable square product of the sum of two terms. The remarkable square product of the difference of two terms. Proof of the truth of the rule of the remarkable square product of the difference of two terms. Plane and metric geometry. Pythagoras' theorem. Applying Pythagoras' theorem to a right triangle contained in a trigonometric circle with center O. Observing the hypotenuse, the greater leg and the lesser leg, etc.