若等腰三角形的两边长分别为3cm和8cm，则它的周长是
当3cm是腰时，3+3＜8，不符合三角形三边关系，故舍去；当8cm是腰时，周长=8+8+3=19cm．
故它的周长为19cm．
故答案为：19cm．
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绛旓細瑙ｏ細鍏堟眰鍑烘柟绋嬬粍{x-2y=-5锛屸憼 {x+2y=11 鈶 鐨勮В锛岀敱鈶+鈶″緱锛歺-2y+x+2y=-5+11.瑙ｄ箣锛屽緱 x=3 灏唜=3甯﹀叆鈶狅紝寰 y=4 鈭存柟绋嬬粍鐨勮В涓猴箾x=3 锕泍=4 鈭垫柟绋嬬粍鐨勮В鏄竴涓绛夎叞涓夎褰㈢殑涓よ竟銆傗埓杩欎袱杈规槸鑵板拰搴曪紝鍋囪锛涒憼3鏄叞锛4浣滀负搴曪紝3+3锛4锛屾垚绔嬨傗憽4鏄叞锛3浣滀负搴...
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