在三角形ABC中，内角A，B，C的对边分别是a，b，c
\u5728\u4e09\u89d2\u5f62ABC\u4e2d,\u4e09\u4e2a\u5185\u89d2\u6ee1\u8db3\u2220B-\u2220A=\u2220C-\u2220B,\u5219\u2220B\u7b49\u4e8e\u2220B-\u2220A=\u2220C-\u2220B \u5f97\u52302B=A+C\uff0c\u53c8\u56e0\u4e3aA+B+C=180\u5ea6 \u6240\u4ee53B=180\uff0cB=60\u5ea6
\u8bbe\u2220B=X\uff0c\u5219\u2220A=x-10,\u2220C=x+10
\u2220A+\u2220B+\u2220C
=x-10+x+x+10
\u89e3\u5f97x=60
\u2220B=60\u00b0
\u2220A=60-10=50\u00b0
\u2220C=60+10=70\u00b0
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