



 
Hi Syed, I reproduced the diagram you sent and added the letters $A, B, C, \mbox{ and }D.$ Is this all you know? The perimeter is $8 + 4 + CD + DA$ and since triangle $ABC$ is a right triangle you can use Pythagoras theorem to show that $CA = \sqrt{8^2 + 4^2} = \sqrt{80}.$ From this information you can't determine $CD$ or $DA,$ all that you can say is that $CD^2 + DA^2 = 80^2.$ Penny  


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