Why is ab+bc+cd+da a monomial?
In the figure, prove that:
(i) CD+DA+AB+BC>2AC
(ii) CD+DA+AB>BC
Let ABCD be a quadrilateral with diagonals AC and BD. Prove the following statements (Compare these with the previous problem);
(a) AB + BC + CD > AD;
(b) AB + BC + CD + DA > 2AC;
(c) AB + BC + CD + DA > 2BD;
(d) AB + BC + CD + DA > AC + BD.