Here http://www.maa.org/sites/default/files/269122948517.pdf you can find Grace Lin's proof without Words that The Product of the Perimeter of a Triangle and Its Inradius Is Twice the Area of the Triangle (see the figure below)

                                    Grace Lin's proof http://www.inp.nsk.su/%7Esilagadz/Lin_proof.jpg

The proof originally appeared in the 1999 October issue of Mathematics Magazine.

Here you can find Grace Lin's proof without Words that The Product of the Perimeter of a Triangle and Its Inradius Is Twice the Area of the Triangle (see the figure below)

The proof originally appeared in the 1999 October issue of Mathematics Magazine.

Here http://www.maa.org/sites/default/files/269122948517.pdf you can find Grace Lin's proof without Words that The Product of the Perimeter of a Triangle and Its Inradius Is Twice the Area of the Triangle. The proof originally appeared in the 1999 October issue of Mathematics Magazine.

Here http://www.maa.org/sites/default/files/269122948517.pdf you can find Grace Lin's proof without Words that The Product of the Perimeter of a Triangle and Its Inradius Is Twice the Area of the Triangle (see the figure below)

                                    Grace Lin's proof http://www.inp.nsk.su/%7Esilagadz/Lin_proof.jpg

The proof originally appeared in the 1999 October issue of Mathematics Magazine.