Contribution for Puzzlet #064

From:  Denis Borris [borrisd@ca.inter.net]


You can solve that "type" by looping only one variable.

Let the sides be a,b and c (c = hypotenuse)

a + b + c + ab/2 = 280
a + b + sqrt(a^2 + b^2) + ab/2 = 280
2sqrt(a^2 + b^2) = 560 - 2a - 2b - ab

square both sides leads to:
a^2(b^2 + 4b) + a(4b^2 - 1112b - 2240) - 2240b + 313600 = 0

let x = b^2 + 4b, y = 4b^2 - 1112b - 2240, z = 313600 - 2240b; then:
xa^2 + ya + z = 0
a = [-y +- sqrt(y^2 - 4xz)] / (2x)

so: loop b, calculate a, c = sqrt(a^2 + b^2)

Not too important to save time here of course (with 280 as total)
but would be if the 280 was a 20 digit (or more) number!

Thanks for this.  I hadn't thought of doing it this way (as the actress said to the bishop).  As you say, an important approach for larger numbers.

Dave.


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