Answer:
3√2
Explanation:
The hypotenuse of an isosceles right triangle is √2 times the side length.
x = 3√2
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All these triangles are similar, so the ratio of hypotenuse to leg is the same for all.
hypotenuse/leg = x/3 = (3+3)/x
x² = 3·6 = 3²·2 . . . . cross multiply (identify square factors)
x = 3√2 . . . . . take the square root