Consecutive Pythagorean Triples methods from the history of math part:2
in the previous article: integer Pythagorean Triples, Methods From the
History of Math Part 1, we discussed a simple algorithm enables us to find integer triples; the current article introduces another method to find
consecutive Pythagorean triples which means triples a,b,c
so that b (one right side) and c(the hypotenuse) are consecutive numbers.
The method based on the short multiplication formula:
(x+y)
2 = x
2+2xy+y
2 Suppose that y=1
We get the equation:
*** (x+1)
2=x
2+2x+1
In both sides we can notice squares of consecutive numbers which are: x and x+1
In order to receive a Pythagorean triple via this formula, the expression 2x+1 must be square of some alue.
In this case the parts of the equation: a2 + b2 = c2 that describes Pythagoras theorem are:
a
2 = 2x+1
b
2 = x
2 c
2= (x+1)
2 lets suppose that 2x+1 is square of the value t.
then 2x+1=t
2 , therefore x=(t
2-1)/2.
we can express the Pythagorean triple
a
2 = 2x+1 = t
2 ====== a=t
b
2 = x
2 ========== b=x ===== b=(t
2-1)/2.
c
2= (x+1)
2 ========== c=x+1 ===== c=(t
2+1)/2 .
Note that if we wan to "build" integer consecutive Pythagorean triples, the value t must be odd number ( try to figure out why??)
Now let us try to find Pythagorean triple using this template: lets chose for example 5 as the the value of t
Then: a= t = 5
b= (25-1)/2 == b=12
c= (25+1)/2 == c=13
this lead to the consecutive triple (5,12,13), and using different odd values of t (t>1) leads us to different consecutive Pythagorean triples.