| 
 
				
				Leonhard Euler 
                (Swiss mathematician and physicist, 1707-1783) and his beautiful and 
				extraordinary formula that links the 5 fundamental constants in 
				Mathematics, namely, e, the base of the natural logarithms, i, 
				the square root of -1, Pi, the ratio of the circumference of a 
				circle to its diameter, 1 and 0, together! 
											
Euler's Equation or Identity 
							
							
				  
							Euler's formula 
							is a mathematical formula in complex analysis that 
							shows a deep relationship between the trigonometric 
							functions and the complex exponential function. 
							 
							Euler's formula states that, for any real number x: 
							(1)  
\(e^{ix}=\cos x+i\cdot \sin x\)  (Euler's formula) 
							where: 
							
							
							Euler's equation or 
							identity is a special case of the Euler' 
							formula, where: 
							(2)  
\(x=\pi \)							
							 
							
							By substitution in (1): 
							(3)  
\(e^{i\pi }=\cos \pi +i\cdot \sin \pi \)							
							 
							(4)  
\(e^{i\pi }=-1+0 \)  
							(5) Therefore:  
\(e^{i\pi }=-1 \) (Euler's Equation or Identity)   
               		  
				Benjamin Peirce 
				(1809-1880, American mathematician, professor at Harvard) gave a 
				lecture proving "Euler's equation", and concluded: 
				"Gentlemen, that is 
				surely true, it is absolutely 
				paradoxical; we cannot understand 
				it, and we don't know 
				what it means. But we have proved 
				it, and therefore we 
				know it must be the truth." 
				  
				Reference: The 
				Changing Shape of Geometry. Celebrating a Century of Geometry 
				and Geometry Teaching. Edited on behalf of The Mathematical 
				Association UK by Chris Pritchard. Cambridge University Press, 
				(Cambridge 2003). 
									 |