Answer:
a) 4
Step-by-step explanation:
Since e, d, and f are midpoints all 4 of the smaller triangles are equal so ad = 5 and ae = 3. pythagorean theorem it up and 5^2 - 3^2 = ed^2
= 25 - 9 = 16
= sqrt 16 = 4
sqrt means square root
