mo1 2年以上以前 参考概略です A(1+2i),B(3),C(7+8i) {(7+8i)-(1+2i)}/{(3)-(1+2i)} =3i =3{cos(π/2)+isin(π/2)} ∠BAC=π/2 補足計算 {(7+8i)-(1+2i)}/{(3)-(1+2i)} ={6(1+i)}/{2(1-i)} ={3(1+i)}/{(1-i)} ={3(1+i)(1+i)}/{(1-i)(1+i)} ={3(2i)}/{2} =3i 留言