【答案】
分析:任何數(shù)的絕對值,以及算術(shù)平方根一定是非負(fù)數(shù),已知中兩個非負(fù)數(shù)的和是0,則兩個一定同時是0;
另外已知直角三角形兩邊x、y的長,具體是兩條直角邊或是一條直角邊一條斜邊,應(yīng)分類討論.
解答:解:∵|x
2-4|≥0,
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,
∴x
2-4=0,y
2-5y+6=0,
∴x=2或-2(舍去),y=2或3,
①當(dāng)兩直角邊是2時,三角形是直角三角形,則斜邊的長為:
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=
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;
②當(dāng)2,3均為直角邊時,斜邊為
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=
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;
③當(dāng)2為一直角邊,3為斜邊時,則第三邊是直角,長是
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=
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.
點評:本題考查了有理數(shù)加法法則,非負(fù)數(shù)的性質(zhì),另外考查勾股定理的應(yīng)用.