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And yet, we somehow think that being able to draw an accurate picture of an ellipse given its equation is useful, along with knowing the derivative of every inv
by j2kun 13y ago
And yet, we somehow think that being able to draw an accurate picture of an ellipse given its equation is useful, along with knowing the derivative of every inverse trig function, and countless other things.
- gus_massa 13y agoI agree that the exact form of an ellipse is not useful, but some general idea is. Other example is the method for long multiplication. I think that it's not 1000 years old, but I can't find a source. One of the formed methods was to use square tables and the identity xy = ( (x+y)^2 - (x-y)^2) )/4. It guesses it was explained in schools, but now it's almost a curiosity. To use it, you must have a book with the tables of the squares, and the last edition of those books is from 1888: http://en.wikipedia.org/wiki/Multiplication_algorithm#Quarter_square_multiplication http://en.wikipedia.org/wiki/Multiplication_algorithm#Quarte...