=a+bi z2=c+di |z1|=3,a^2+b^2=9 |z2|=5,c^2+d^2=25 |z1-z2|=7,|a+bi-c-di|=|(a-c)+(b-d)i|=7,(a-c)^2+(b-d)^2=49 --> a^2-2ac+c^2+b^2-2bd+d^2=49 --> a^2+b^2+c^2+d^2-2(ac+bd)=49 --> 9+25-2(ac+bd)=49 --> 2(ac+...