梯形,知道高度和坡比,还有下底。怎么算上底 已知梯形的下底，高，和坡比，怎样计算上底
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\u901a\u8fc7\u5761\u6bd4\u4e0e\u9ad8\uff0c\u5229\u7528\u4e09\u89d2\u51fd\u6570\uff0c
\u53ef\u6c42BE\u4e0eCF\uff0c
\u4e0a\u5e95AD=\u4e0b\u5e95BC-(BE+CF)\u3002
x=d-h/a
绛旓細涓婂簳x 锛屾尝姣旓細a=h/锛坉-x锛変唬鍏ユ暟鍊兼尝姣攁銆楂樺害h锛涓嬪簳d 锛涜В鍑烘潵寰楀埌 x=d-h/a
绛旓細棰囨瘮鐨勮瘽涓鑸兘鏄潯鐨勫瀭鐩翠笅鏉ワ紝鎶曞奖鍦涓嬪簳涓婇潰鐨勯偅涓暱搴﹂櫎浠ュ潯銆傞偅涔堜綘鍙渶瑕佺煡閬撱傞偅涓姇褰卞闀匡紝鑰屾姇褰辨槸绛変簬涓嬪簳鍑忎笂搴曠殑銆備綘灏卞彲浠ュ垪鏂圭▼寮忋傚垎鍒眰鍑轰粬浠殑鐮寸唤銆
绛旓細棣栧厛鍧℃瘮灏辨槸鍧￠潰鍨傜洿楂樺害姣斾笂涓嬪簳鍜屼笂搴曞樊锛屽嵆1锛1.5锛4.4锛氾紙涓嬪簳锛嶄笂搴曪級锛岃繖鏍峰彲浠ヨВ鍑轰笅搴曚笌涓婂簳涔嬪樊鏄6.6锛屼笂搴曟槸0.1锛岃屾褰㈤潰绉氨鏄紙涓婂簳锛嬩笅搴曪級/2脳楂樺害锛濓紙0.1+6.7锛/2脳4.4锛14.69m²銆
绛旓細鍥炵瓟锛氫緷棰樻剰,姹俠,宸茬煡h=2.5 a=0.2 鍧℃瘮=h/L=1/0.3,甯﹀叆h=2.5,鍙互寰桳=2.5*0.3/1=0.75,鑰宐=a+L,甯﹀叆a鍜孡鐨勫煎緱鍒癰=0.75+0.2=0.95
绛旓細妯垏闈㈡槸鐩磋姊舰鐨勮瘽锛涓嬪簳=5+3*3=14绫炽傚鏋滃垏闈㈡槸绛夎叞姊舰鐨勮瘽锛屼笅搴=5+3*3*2=23绫
绛旓細渚濋鎰忥紝姹俠锛屽凡鐭=2.5 a=0.2 鍧℃瘮=h/L=1/0.3锛屽甫鍏=2.5,鍙互寰桳=2.5*0.3/1=0.75,鑰宐=a+L,甯﹀叆a鍜孡鐨勫煎緱鍒癰=0.75+0.2=0.95
绛旓細濡傚浘锛屼负姊舰鐨勫彸鍗婇儴鍒嗐鍧℃瘮=h/l l=h/鍧℃瘮 鐢ㄥ悓鏍锋柟娉曡绠楋紝宸﹀崐閮ㄥ垎鐨刲锛岃涓簂鈥叉褰㈢殑涓嬪簳=涓婂簳+l+l鈥
绛旓細鍥炵瓟锛鍧″害姣 =楂樺樊/姘村钩璺濈, 鍓╀笅閮ㄥ垎鐣欑粰鎮ㄧ粌涔,鍙互鍚?
绛旓細浠庝笂搴曠殑涓ら《鐐瑰悜涓嬪仛鍨傜嚎锛屼袱杈规槸涓や釜鍏ㄧ瓑鐨勭洿瑙掍笁瑙掑舰 鍧″害灏辨槸搴曡鐨勬鍒囧硷紝鏍规嵁楂樺拰鍧″害鍙互璁＄畻閭ｄ袱涓洿瑙掍笁瑙掑舰鐨搴 涓嬪簳=涓婂簳鍔犱笂杩欎袱娈 0.74脳1.5脳2+26=28.2
绛旓細棣栧厛锛屽潯搴︽瘮鏄杈规瘮閭昏竟 鍥犱负鍧″害姣斾负1锛0.3 鎵浠ュ彲鐭ラ偦杈逛负锛3.35脳0.3=1.005绫 鑰屼笂搴曚负0.5绫筹紝鍒涓嬪簳涓猴細0.5+1.005脳2=2.51绫
