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jmc

geometry junior

Problem

The hypotenuse of a right triangle whose legs are consecutive whole numbers is 29 units. What is the sum of the lengths of the two legs?
Solution
Let's call the length of the shorter leg . Then the length of the longer leg is . Using the Pythagorean Theorem, we write the equation and solve for . Expanding , we get . This can be simplified to , or . Factoring out on the left, we can rewrite it as . In other words, the product of these two consecutive numbers is 420, which means they must each be close to the square root of 420. Indeed, , so the legs must be 20 and 21. Their sum is .
Final answer
41