Problem 5:
[tex]db {}^{2} - ab {}^{2} = ab {}^{2} - ae {}^{2} \\ db {}^{2} = 2ab {}^{2} - ae {}^{2} \\ (ac + bc) {}^{2} = 2ab {}^{2} - ae {}^{2} \\ ac {}^{2} + bc {}^{2} + 2ac.bc = 2ab {}^{2} - ae {}^{2} \\ 2ac.bc = ab {}^{2} - ae {}^{2} [/tex]
[tex]2ac.bc = ab {}^{2} - (ac {}^{} - ce) {}^{2} \\ 2ac.bc = ab {}^{2} - ac {}^{2} + 2ac.ce - ce {}^{2} \\ 2ac.bc = ab {}^{2} - ac {}^{2} - cb {}^{2} + 2ac.ce \\ but \: ab {}^{2} - ac {}^{2} - cb {}^{2} = 0 \\ 2ac.bc = 2ac.ce \\ bc = ce \\ which \: is \: true[/tex]
