把一张长方形纸如图那样折起来，其中∠1=30°，你知道∠2等于多少度吗 下图是一张长方形折起来以后的图形，其中∠1=30°，你知道∠...
\u4e0b\u9762\u662f\u4e00\u5f20\u957f\u65b9\u5f62\u7eb8\u6298\u8d77\u6765\u4ee5\u540e\u7684\u56fe\u5f62\uff0c\u5176\u4e2d\u22201=60\u00b0\uff0c\u6c42\u22202\u591a\u5c11\u5ea6\uff1f\u22202=\uff08180\u00b0-\u22201\uff09\u00f72=\uff08180\u00b0-60\u00b0\uff09\u00f72=120\u00b0\u00f72=60\u00b0
\u89d2:\u4ece\u4e00\u70b9\u5f15\u51fa\u4e24\u6761\u5c04\u7ebf\uff0c\u5c31\u7ec4\u6210\u4e00\u4e2a\u89d2\u3002\u901a\u5e38\u7528\u7b26\u53f7\u201c\u2220\u201d\u6765\u8868\u793a\uff0c\u89d2\u7684\u5927\u5c0f\u770b\u4e24\u6761\u8fb9\u53c9\u5f00\u7684\u5927\u5c0f\uff0c\u53c9\u5f00\u7684\u8d8a\u5927\uff0c\u89d2\u5c31\u8d8a\u5927\u3002\u89d2\u7684\u5927\u5c0f\u4e0e\u89d2\u4e24\u6761\u8fb9\u7684\u957f\u77ed\u6ca1\u6709\u5173\u7cfb\u3002
\u89d2\u7684\u8ba1\u91cf\u5355\u4f4d\uff1a\u89d2\u7684\u8ba1\u91cf\u5355\u4f4d\u662f\u201c\u5ea6\u201d\uff0c\u7528\u7b26\u53f7\u201c\u00b0\u201d\u8868\u793a\uff0c\u628a\u534a\u5706\u5206\u6210180\u7b49\u4efd\uff0c\u6bcf\u4e00\u4efd\u6240\u5bf9\u7684\u89d2\u7684\u5927\u5c0f\u662f1\u5ea6\uff0c\u8bb0\u4f5c1\u00b0\u3002
\u62d3\u5c55\uff1a
\u76f4\u7ebf\uff1a\u628a\u7ebf\u6bb5\u7684\u4e24\u7aef\u65e0\u9650\u5ef6\u957f\uff0c\u53ef\u4ee5\u5f97\u5230\u4e00\u6761\u76f4\u7ebf\uff1b\u76f4\u7ebfl\uff0c\u76f4\u7ebfAB\u5c04\u7ebf\uff1a\u628a\u7ebf\u6bb5\u7684\u4e00\u7aef\u65e0\u9650\u5ef6\u957f\uff0c\u53ef\u4ee5\u5f97\u5230\u4e00\u6761\u5c04\u7ebf\uff1b\u5c04\u7ebfAB\u5c04\u7ebf\u6709\u4e00\u4e2a\u7aef\u70b9\uff0c\u76f4\u7ebf\u6ca1\u6709\u7aef\u70b9\u3002 \u7ebf\u6bb5:\u7528\u76f4\u5c3a\u628a\u4e24\u70b9\u8fde\u63a5\u8d77\u6765\uff0c\u5c31\u53ef\u4ee5\u5f97\u5230\u4e00\u6761\u7ebf\u6bb5\uff1b\u7ebf\u6bb5\u662f\u76f4\u7ebf\u7684\u4e00\u90e8\u5206\u3002\u7ebf\u6bb5AB\uff0c\u7ebf\u6bb5a\u7ebf\u6bb5\u6709\u4e24\u4e2a\u7aef\u70b9\uff0c\u5b83\u7684\u957f\u5ea6\u662f\u6709\u9650\u7684\uff0c\u7ebf\u6bb5\u7684\u957f\u5c31\u662f\u4e24\u70b9\u95f4\u7684\u8ddd\u79bb\uff1b
75\u00b0
如图，∠2=（180°-30°）÷2
=150°÷2
=75°．
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绛旓細AF脳AE=7 DE脳DC=21 AE=DE锛屾墍浠C=3AF 鎵浠F=2AF 鍥犱负BF=EF锛屾墍浠F=2AF锛屾墍浠E=鈭3AF 鎵浠F=鈭21/3 鎵浠E=鈭7 鎵浠D=2鈭7
绛旓細鎶樺彔鏈鍩烘湰鍘熷垯锛岃閲嶅悎銆傗埖鈭燗OB鈥=46掳锛屸埓鈭燘OB鈥=180掳-46掳=134掳锛岀敱鎶樺彔鐭ワ細鈭燘鈥極G=1/2鈭燘OB鈥=67掳銆
绛旓細鐒跺悗鐢21鍑7寰14銆傚啀鐢ㄤ笁瑙掑舰EDC鐨勯潰绉櫎涓夎褰FE闈㈢Н绛変簬3锛屽洜涓哄畠浠殑楂樼浉绛夛紝鐢辨鍙湅鍑篋C鏄疉F鐨3鍊嶃傜劧鍚庡垪鏂圭▼锛氳AF涓簒锛屽垯DC涓3x锛3x脳DE-x脳EA=14鍥犱负ED=EAx=7鎵浠F=7, CD=7涔3绛変簬21,DE=21闄や互21=1鍥犱负ED涓嶢E鐩哥瓑鎵浠D=1涔2绛変簬2闀挎柟褰闈㈢Н绛変簬2涔21绛変簬42銆
绛旓細寰堢畝鍗曠殑闂鍛锛(180掳-36掳)/2灏辨槸浜
绛旓細瑙 鏄撹瘉鈻矨EF鈭解柍BCE 鈭碅E*BE=AF*BC 鈭碘柍AEF闈㈢Н涓3.5 鈻矪CE闈㈢Н涓10.5 E鏄疉B涓偣 鈭碅1/3BC 鈭碅E*BE=AF*BC 璁続F=a 鍒3a^2=AE^2 鈭碅E=鈭3a 鈭碘柍AEF闈㈢Н涓3.5 鈭1/2a*鈭3a=3.5 鈭粹垰3a^2=7 鈭碅BCD 鐨勯潰绉=AB*CD=2鈭3a*3a=6鈭3a^2=42 ...
绛旓細鐢卞鎶樼殑鎬ц川鍙煡鈭3=鈭2锛屽洜涓猴紝鈭1+鈭2+鈭3=180掳锛屸垹1=30掳锛屾墍浠モ垹2+鈭3=150掳锛屸垹2=150掳梅2=75掳銆
绛旓細鈭2锛濓紙180-48锛壝2锛66
绛旓細鐢卞垎鏋愬彲鐭ワ紝鈭2=锛180掳-鈭1锛壝2 =锛180掳-40掳锛壝2 =140掳梅2 =70掳锛庣瓟锛氣垹2鐨勫害鏁版槸70掳锛涙晠绛旀涓猴細70锛
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