August 31, 2012

Gambar Ilusi Optik Yang Menipu Mata

• Persegi Sama Sisi



Ini adalah persegi yang sisinya sama panjang.

• Lengkung atau Lurus


cek pake penggaris

• Bulat atau Benjol



Lingkarannya sempurna,  Silakan dibuktikan dengan jangka.


• Lurus atau Melengkung



Garis vertikal merah 100% lurus dan tidak melengkung.


August 30, 2012

Leonhard Euler (1707 – 1783)


From `A Short Account of the History of Mathematics’ (4th edition, 1908) by W. W. Rouse Ball.

Leonhard Euler was born at Bâle on April 15, 1707, and died at St. Petersburg on September 7, 1783. he was the son of a Lutheran minister who had settled at Bâle, and was educated in his native town under the direction of John Bernoulli, with whose sons Daniel and Nicholas he formed a lifelong friendship. When, in 1725, the younger Bernoullis went to Russia, on the invitation of the empress, they procured a place there for Euler, which in 1733 he exchanged for the chair of mathematics, then vacated by Daniel Bernoulli. The severity of the climate affected his eyesight, and in 1735 he lost the use of one eye completely. In 1741 he moved to Berlin at the request, or rather command, of Frederick the Great; here he stayed till 1766, when he returned to Russia, and was succeeded at Berlin by Lagrange. Within two or three years of his going back to St. Petersburg he became blind; but in spite of this, and although his house, together with many of his papers, were burnt in 1771, he recast and improved most of his earlier works. He died of apoplexy in 1783. He was married twice.

I think we may sum up Euler’s work by saying that he created a good deal of analysis, and revised almost all the branches of pure mathematics which were then known, filling up the details, adding proofs, and arranging the whole in a consistent form. Such work is very important, and it is fortunate for science when it fall into hands as competent as those of Euler.