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9514 1404 393
Answer:
√7
Step-by-step explanation:
The Pythagorean theorem tells you the square of the hypotenuse is equal to the sum of the squares of the sides. Let x represent the unknown side. Then we have ...
x² +9² = (√88)²
x² +81 = 88
x² = 7 . . . subtract 81; next, take the (positive) square root
x = √7 . . . . the third side