+97 In rectangle ABCD, AB=3 and BC=9 . The rectangle is folded so that points A and C coincide, forming the pentagon ABEFD. What is the length of segment EF? Express your answer in simplest radical form.
+97 The answer I got is sqrt10. This is how I got it (and its correct)
To begin with, let DF=x and FA = 9-x . is a right triangle, so we can solve for x by applying the Pythagorean Theorem:.
Once you solved for x you can find FA=EA=5, then PE= 5-4 =1. And Da=3 , so EF will be sqrt(9+1) or sqrt10
