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Helppppp mathhhhhhhhhhh

Helppppp mathhhhhhhhhhh-example-1

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DEF is a isosceles right triangle, so DE =EF. apply Pythagoras:

DF² = DE² + EF² , BUT DE = DF .then DB² = 2DE² = 28²

DE² = 28/2 = 14 and DE = √14 = 3.71 ≈3.7