(e) Let the ladder be placed in the position AC first. After drawing out the base of the ladder the new position of the ladder becomes ED. According to the question AD=x,EC=2x BC=7,AC=25 ∴AB=24 In ΔDBE,DB2+BE2=DE2 ⇒(24−x)2+(7+2x)2=252 ⇒242−48x+x2+72+28x+4x2=252 ⇒5x2=20x⇒x=4(∵x≠0) ∴EC=8