| 面積達を使い;
In[2]:= s = (8 + 9 + 6)/2; s1 = (8 + 5 + m)/2; s2 = (4 + 6 + m)/2;
In[5]:= Sqrt[s*(s - 8)*(s - 9)*(s - 6)] == Sqrt[s1*(s1 - 8)*(s1 - 5)*(s1 - m)] + Sqrt[s2*(s2 - 4)*(s2 - 6)*(s2 - m)]
Out[5]= Sqrt[8855]/4 == Sqrt[(10 + m)*(-6 + (10 + m)/2)* (-4 + (10 + m)/2)*(-m + (10 + m)/2)]/ Sqrt[2] + Sqrt[(13 + m)*(-8 + (13 + m)/2)* (-5 + (13 + m)/2)*(-m + (13 + m)/2)]/ Sqrt[2]
In[6]:= Solve[%, m]
Out[6]= {{m -> -(16/3)}, {m -> 16/3<------です}, {m -> -3*Sqrt[771/71]}, {m -> 3*Sqrt[771/71]}}
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