zhí角jiǎo三sān角jiǎo形xíng中一yī直zhí角jiǎo边biān的长zhǎng为wèi9，另lìng两liǎng边biān为wèi连lián续自zì然rán数shù，则zé直zhí角jiǎo三sān角jiǎo形xíng的周zhōu长zhǎng为wèi

A.121B.120C.90D.不能确què定dìng,C解jiě析xī分fēn析xī：连lián续自zì然rán数shù，两liǎng数shù的差chà是shì1，较jiào大dà的是shì斜xié边biān，根gēn据jù勾gōu股gǔ定dìng理lǐ就jiù可kě解jiě得dé．

解jiě答dá：设另lìng一yī直zhí角jiǎo边biān为wèia，斜xié边biān为wèia+1．根gēn据jù勾gōu股gǔ定dìng理lǐ可kě得dé，（a+1）2-a2=92．解jiě之zhī得déa=40．则zéa+1=41，则zé直zhí角jiǎo三sān角jiǎo形xíng的周zhōu长zhǎng为wèi9+40+41=90．故选C．

点评píng：本题tí综zōng合考查了le勾gōu股gǔ定dìng理lǐ，解jiě这zhè类lèi题tí的关键jiàn是shì利用yòng直zhí角jiǎo三sān角jiǎo形xíng，用yòng勾gōu股gǔ定dìng理lǐ来lái寻xún求qiú未wèi知zhī系数shù的等děng量liàng关系．