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ΔABC dreptunghic, masura unghiului BAC=90°.Fie AD perpendiculara pe BC, D apartinand dreptei BC. AB=300 m DC=320 m
Aflati BC.

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Miky93ask
ΔABC, mas<A=90
AB²=BD*BC
AB²=BD(BD+DC)
90 000=BD²+320BD
BD²+320BD-90 000=0
BD²+320BD+25600 -115600=0
(BD+160)²-115600=0
[(BD+160)-340][(BD+160)+340]=0
(BD-180)(BD+500)=0
BD-180=0     BD+500=0
BD=180        BD=-500    BD∈N   ⇒BD=180
BC=180+320
BC=500

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