Answer
If A,B,C are the squares of the three sides, the answer is the
squareroot of A+B+C. We don't need to work out the sides, which
are irrational numbers.
Pythagoras tells us that:
A+B = 40 x 40 = 1600
B+C = 43 x 43 = 1849
A +C = 51 x 51 = 2601
Adding these three equations:
2A+2B+2C = 1600+1849+2601 = 6050
halving
A+B+C = 3025
so the answer is the square root of 3025 which is 55.
I received only one answer, from John Stafford, so there was
no draw this month. Thanks to John for his analysis of the
problem.
